Re-introduce TX FIFO resize for larger EP bursting

Some UDCs may have constraints on how many high bandwidth endpoints it can support in a certain configuration. This API allows for the composite driver to pass down the total number of endpoints to the UDC so it can verify it has the required resources to support the configuration.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/gadget/udc/core.c | 9 +++++++++
 include/linux/usb/gadget.h    | 2 ++
 2 files changed, 11 insertions(+)

drivers/usb/gadget/udc/core.c +0 -0

index 4173acd..469962f 100644

Hi Wesley,

Quoted 19 lines · Wesley Cheng

Some UDCs may have constraints on how many high bandwidth endpoints it can support in a certain configuration. This API allows for the composite driver to pass down the total number of endpoints to the UDC so it can verify it has the required resources to support the configuration.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/gadget/udc/core.c | 9 +++++++++
 include/linux/usb/gadget.h    | 2 ++
 2 files changed, 11 insertions(+)

drivers/usb/gadget/udc/core.c +0 -0

index 4173acd..469962f 100644
@@ -1003,6 +1003,15 @@ int usb_gadget_ep_match_desc(struct usb_gadget *gadget,
 }
 EXPORT_SYMBOL_GPL(usb_gadget_ep_match_desc);
 

drivers/usb/gadget/udc/core.c int usb_gadget_ep_match_desc(struct usb_gadget *gadget, · line 1006

Quoted 1 line

drivers/usb/gadget/udc/core.c +1 -0

+int usb_gadget_check_config(struct usb_gadget *gadget, unsigned long ep_map)

You should probably add a kernel-doc for this function.

Jack

Some UDCs may have constraints on how many high bandwidth endpoints it can support in a certain configuration. This API allows for the composite driver to pass down the total number of endpoints to the UDC so it can verify it has the required resources to support the configuration.

Signed-off-by Wesley Cheng <[email protected]>

include/linux/usb/gadget.h +1 -0

@@ -328,6 +328,7 @@ struct usb_gadget_ops {
 	struct usb_ep *(*match_ep)(struct usb_gadget *,
 			struct usb_endpoint_descriptor *,
 			struct usb_ss_ep_comp_descriptor *);
+	int	(*check_config)(struct usb_gadget *gadget, unsigned long ep_map);
 };
 
 /**

Quoted 19 lines · Wesley Cheng

Some UDCs may have constraints on how many high bandwidth endpoints it can support in a certain configuration. This API allows for the composite driver to pass down the total number of endpoints to the UDC so it can verify it has the required resources to support the configuration.

Signed-off-by Wesley Cheng <[email protected]>

include/linux/usb/gadget.h +1 -0

@@ -328,6 +328,7 @@ struct usb_gadget_ops {
 	struct usb_ep *(*match_ep)(struct usb_gadget *,
 			struct usb_endpoint_descriptor *,
 			struct usb_ss_ep_comp_descriptor *);
+	int	(*check_config)(struct usb_gadget *gadget, unsigned long ep_map);
 };
 
 /**

include/linux/usb/gadget.h int usb_gadget_connect(struct usb_gadget *gadget); · line 614

Quoted 7 lines

include/linux/usb/gadget.h +1 -0

@@ -607,6 +608,7 @@ int usb_gadget_connect(struct usb_gadget *gadget);
 int usb_gadget_disconnect(struct usb_gadget *gadget);
 int usb_gadget_deactivate(struct usb_gadget *gadget);
 int usb_gadget_activate(struct usb_gadget *gadget);
+int usb_gadget_check_config(struct usb_gadget *gadget, unsigned long ep_map);
 #else
 static inline int usb_gadget_frame_number(struct usb_gadget *gadget)
 { return 0; }

Don't you also need an entry for the case where CONFIG_USB_GADGET isn't enabled?

Alan Stern

Some devices have USB compositions which may require multiple endpoints that support EP bursting. HW defined TX FIFO sizes may not always be sufficient for these compositions. By utilizing flexible TX FIFO allocation, this allows for endpoints to request the required FIFO depth to achieve higher bandwidth. With some higher bMaxBurst configurations, using a larger TX FIFO size results in better TX throughput.

By introducing the check_config() callback, the resizing logic can fetch the maximum number of endpoints used in the USB composition (can contain multiple configurations), which helps ensure that the resizing logic can fulfill the configuration(s), or return an error to the gadget layer otherwise during bind time.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |   8 ++
 drivers/usb/dwc3/ep0.c    |   2 +
 drivers/usb/dwc3/gadget.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

drivers/usb/dwc3/core.c +0 -0

index 6969196..e7fa6af 100644

drivers/usb/dwc3/core.c +0 -0

 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");

drivers/usb/dwc3/core.h +8 -0

index eec1cf4..983b2fd4 100644
@@ -1223,6 +1223,7 @@ struct dwc3 {
 	unsigned		is_utmi_l1_suspend:1;
 	unsigned		is_fpga:1;
 	unsigned		pending_events:1;
+	unsigned		needs_fifo_resize:1;
 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;

@@ -1257,6 +1258,10 @@ struct dwc3 {
 	unsigned		dis_split_quirk:1;
 
 	u16			imod_interval;
+
+	int			max_cfg_eps;
+	int			last_fifo_depth;
+	int			num_ep_resized;
 };
 
 #define INCRX_BURST_MODE 0

@@ -1471,6 +1476,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 		u32 param);
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_init(struct dwc3 *dwc)
 { return 0; }

@@ -1490,6 +1496,8 @@ static inline int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 		int cmd, u32 param)
 { return 0; }
+static inline void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{ }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)

drivers/usb/dwc3/ep0.c +2 -0

index 8b668ef..4f216bd 100644
@@ -616,6 +616,8 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 		return -EINVAL;
 
 	case USB_STATE_ADDRESS:
+		dwc3_gadget_clear_tx_fifos(dwc);
+
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
 		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

drivers/usb/dwc3/gadget.c +194 -0

index 86f257f..26f9d64 100644
@@ -615,6 +615,161 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
 		bool interrupt);
 
+static int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)
+{
+	int max_packet = 1024;
+	int fifo_size;
+	int mdwidth;
+
+	mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
+	/* MDWIDTH is represented in bits, we need it in bytes */
+	mdwidth >>= 3;
+
+	fifo_size = mult * ((max_packet + mdwidth) / mdwidth) + 1;
+	return fifo_size;
+}
+
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{
+	struct dwc3_ep *dep;
+	int fifo_depth;
+	int size;
+	int num;
+
+	if (!dwc->needs_fifo_resize)
+		return;
+
+	/* Read ep0IN related TXFIFO size */
+	dep = dwc->eps[1];
+	size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	if (DWC3_IP_IS(DWC31))
+		fifo_depth = DWC31_GTXFIFOSIZ_TXFDEP(size);
+	else
+		fifo_depth = DWC3_GTXFIFOSIZ_TXFDEP(size);
+
+	dwc->last_fifo_depth = fifo_depth;
+	/* Clear existing TXFIFO for all IN eps except ep0 */
+	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM);
+	     num += 2) {
+		dep = dwc->eps[num];
+		/* Don't change TXFRAMNUM on usb31 version */
+		size = DWC3_IP_IS(DWC31) ?
+			dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1)) &
+				   DWC31_GTXFIFOSIZ_TXFRAMNUM : 0;
+
+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+	}
+	dwc->num_ep_resized = 0;
+}
+
+/*
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In general, FIFO depths are represented with the following equation:
+ *
+ * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+ *
+ * Conversions can be done to the equation to derive the number of packets that
+ * will fit to a particular FIFO size value.
+ */
+static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	int fifo_0_start;
+	int ram1_depth;
+	int fifo_size;
+	int min_depth;
+	int num_in_ep;
+	int remaining;
+	int mult = 1;
+	int fifo;
+	int tmp;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* resize IN endpoints except ep0 */
+	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
+		return 0;
+
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+
+	if ((dep->endpoint.maxburst > 1 &&
+	     usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
+	    usb_endpoint_xfer_isoc(dep->endpoint.desc))
+		mult = 3;
+
+	if (dep->endpoint.maxburst > 6 &&
+	    usb_endpoint_xfer_bulk(dep->endpoint.desc) && DWC3_IP_IS(DWC31))
+		mult = 6;
+
+	/* FIFO size for a single buffer */
+	fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
+
+	/* Calculate the number of remaining EPs w/o any FIFO */
+	num_in_ep = dwc->max_cfg_eps;
+	num_in_ep -= dwc->num_ep_resized;
+
+	/* Reserve at least one FIFO for the number of IN EPs */
+	min_depth = num_in_ep * (fifo + 1);
+	remaining = ram1_depth - min_depth - dwc->last_fifo_depth;
+
+	/*
+	 * We've already reserved 1 FIFO per EP, so check what we can fit in
+	 * addition to it.  If there is not enough remaining space, allocate
+	 * all the remaining space to the EP.
+	 */
+	fifo_size = (mult - 1) * fifo;
+	if (remaining < fifo_size) {
+		if (remaining > 0)
+			fifo_size = remaining;
+		else
+			fifo_size = 0;
+	}
+
+	fifo_size += fifo;
+	/* Last increment according to the TX FIFO size equation */
+	fifo_size++;
+
+	/* Check if TXFIFOs start at non-zero addr */
+	tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);
+
+	fifo_size |= (fifo_0_start + (dwc->last_fifo_depth << 16));
+	if (DWC3_IP_IS(DWC31))
+		dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+	else
+		dwc->last_fifo_depth += DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);
+
+	/* Check fifo size allocation doesn't exceed available RAM size. */
+	if (dwc->last_fifo_depth >= ram1_depth) {
+		dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
+			dwc->last_fifo_depth, ram1_depth,
+			dep->endpoint.name, fifo_size);
+		if (DWC3_IP_IS(DWC31))
+			fifo_size = DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+		else
+			fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);
+		dwc->last_fifo_depth -= fifo_size;
+		return -ENOMEM;
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dwc->num_ep_resized++;
+
+	return 0;
+}
+
 /**
  * __dwc3_gadget_ep_enable - initializes a hw endpoint
  * @dep: endpoint to be initialized

@@ -632,6 +787,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	int			ret;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
+		ret = dwc3_gadget_resize_tx_fifos(dep);
+		if (ret)
+			return ret;
+
 		ret = dwc3_gadget_start_config(dep);
 		if (ret)
 			return ret;

@@ -2418,6 +2577,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	free_irq(dwc->irq_gadget, dwc->ev_buf);

@@ -2485,6 +2645,39 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 	return 0;
 }
 
+static int dwc3_gadget_check_config(struct usb_gadget *g, unsigned long ep_map)
+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,

@@ -2495,6 +2688,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */

Signature · 2 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

On Thu 21 Jan 22:01 CST 2021, Wesley Cheng wrote:

Under what circumstances should we specify this? And in particular are there scenarios (in the Qualcomm platforms) where this must not be set? The TXFIFO dynamic allocation is actually a feature within the DWC3

In particular, the composition can be changed in runtime, so should we set this for all Qualcomm platforms?

And if that's the case, can we not just set it from the qcom driver?

Regards,
Bjorn

Quoted 2 lines · Bjorn Andersson

On Thu 21 Jan 22:01 CST 2021, Wesley Cheng wrote:

Hi Bjorn,

Quoted 4 lines

Under what circumstances should we specify this? And in particular are there scenarios (in the Qualcomm platforms) where this must not be set? The TXFIFO dynamic allocation is actually a feature within the DWC3

controller, and isn't specifically for QCOM based platforms. It won't do any harm functionally if this flag is not set, as this is meant for enhancing performance/bandwidth.

Quoted 3 lines

In particular, the composition can be changed in runtime, so should we set this for all Qualcomm platforms?

Ideally yes, if we want to increase bandwith for situations where SS endpoint bursting is set to a higher value.

Quoted 2 lines

And if that's the case, can we not just set it from the qcom driver?

Since this is a common DWC3 core feature, I think it would make more sense to have it in DWC3 core instead of a vendor's DWC3 glue driver.

Quoted 18 lines · Wesley Cheng

Quoted 2 lines · Bjorn Andersson

On Thu 21 Jan 22:01 CST 2021, Wesley Cheng wrote:

Hi Bjorn,

Quoted 4 lines

Under what circumstances should we specify this? And in particular are there scenarios (in the Qualcomm platforms) where this must not be set? The TXFIFO dynamic allocation is actually a feature within the DWC3

controller, and isn't specifically for QCOM based platforms. It won't do any harm functionally if this flag is not set, as this is meant for enhancing performance/bandwidth.

Quoted 3 lines

In particular, the composition can be changed in runtime, so should we set this for all Qualcomm platforms?

Quoted 8 lines

Ideally yes, if we want to increase bandwith for situations where SS endpoint bursting is set to a higher value.

Quoted 2 lines

And if that's the case, can we not just set it from the qcom driver?

Since this is a common DWC3 core feature, I think it would make more sense to have it in DWC3 core instead of a vendor's DWC3 glue driver.

I don't have any objections to implementing it in the core driver, but my question is can we just skip the DT binding and just enable it from the vendor driver?

Regards,
Bjorn

Quoted 29 lines · Bjorn Andersson

Quoted 18 lines · Wesley Cheng

Quoted 2 lines · Bjorn Andersson

On Thu 21 Jan 22:01 CST 2021, Wesley Cheng wrote:

Hi Bjorn,

Quoted 4 lines

Under what circumstances should we specify this? And in particular are there scenarios (in the Qualcomm platforms) where this must not be set? The TXFIFO dynamic allocation is actually a feature within the DWC3

controller, and isn't specifically for QCOM based platforms. It won't do any harm functionally if this flag is not set, as this is meant for enhancing performance/bandwidth.

Quoted 3 lines

In particular, the composition can be changed in runtime, so should we set this for all Qualcomm platforms?

Quoted 8 lines

Ideally yes, if we want to increase bandwith for situations where SS endpoint bursting is set to a higher value.

Quoted 2 lines

And if that's the case, can we not just set it from the qcom driver?

Since this is a common DWC3 core feature, I think it would make more sense to have it in DWC3 core instead of a vendor's DWC3 glue driver.

Quoted 7 lines

I don't have any objections to implementing it in the core driver, but my question is can we just skip the DT binding and just enable it from the vendor driver?

Regards,
Bjorn

Hi Bjorn,

I see. I think there are some designs which don't have a DWC3 glue driver, so assuming there may be other platforms using this, there may not always be a vendor driver to set this.

Quoted 38 lines · Wesley Cheng

Quoted 29 lines · Bjorn Andersson

Quoted 18 lines · Wesley Cheng

Quoted 2 lines · Bjorn Andersson

On Thu 21 Jan 22:01 CST 2021, Wesley Cheng wrote:

Hi Bjorn,

Quoted 4 lines

Under what circumstances should we specify this? And in particular are there scenarios (in the Qualcomm platforms) where this must not be set? The TXFIFO dynamic allocation is actually a feature within the DWC3

controller, and isn't specifically for QCOM based platforms. It won't do any harm functionally if this flag is not set, as this is meant for enhancing performance/bandwidth.

Quoted 3 lines

In particular, the composition can be changed in runtime, so should we set this for all Qualcomm platforms?

Quoted 8 lines

Ideally yes, if we want to increase bandwith for situations where SS endpoint bursting is set to a higher value.

Quoted 2 lines

And if that's the case, can we not just set it from the qcom driver?

Since this is a common DWC3 core feature, I think it would make more sense to have it in DWC3 core instead of a vendor's DWC3 glue driver.

Quoted 7 lines

I don't have any objections to implementing it in the core driver, but my question is can we just skip the DT binding and just enable it from the vendor driver?

Regards,
Bjorn

Quoted 6 lines

Hi Bjorn,

I see. I think there are some designs which don't have a DWC3 glue driver, so assuming there may be other platforms using this, there may not always be a vendor driver to set this.

You mean that there are implementations of dwc3 without an associated glue driver that haven't yet realized that they need this feature?

I would suggest then that we implement the core code necessary, we enable it from the Qualcomm glue layer and when someone realize that they need this without a glue driver it's going to be trivial to add the DT binding.

Quoted 1 line

The alternative is that we're lugging around a requirement to specify this property in all past, present and future Qualcomm dts files - and then we'll need to hard code it for ACPI anyways.

Regards,
Bjorn

Some devices have USB compositions which may require multiple endpoints that support EP bursting. HW defined TX FIFO sizes may not always be sufficient for these compositions. By utilizing flexible TX FIFO allocation, this allows for endpoints to request the required FIFO depth to achieve higher bandwidth. With some higher bMaxBurst configurations, using a larger TX FIFO size results in better TX throughput.

By introducing the check_config() callback, the resizing logic can fetch the maximum number of endpoints used in the USB composition (can contain multiple configurations), which helps ensure that the resizing logic can fulfill the configuration(s), or return an error to the gadget layer otherwise during bind time.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |   8 ++
 drivers/usb/dwc3/ep0.c    |   2 +
 drivers/usb/dwc3/gadget.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

drivers/usb/dwc3/core.c +2 -0

index 6969196..e7fa6af 100644
@@ -1284,6 +1284,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				&tx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,tx-max-burst-prd",
 				&tx_max_burst_prd);
+	dwc->needs_fifo_resize = device_property_read_bool(dev,
+							   "tx-fifo-resize");
 
 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");

drivers/usb/dwc3/core.h +0 -0

index eec1cf4..983b2fd4 100644

drivers/usb/dwc3/core.h +3 -0

 #define INCRX_BURST_MODE 0

@@ -1471,6 +1476,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 		u32 param);
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_init(struct dwc3 *dwc)
 { return 0; }

@@ -1490,6 +1496,8 @@ static inline int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 		int cmd, u32 param)
 { return 0; }
+static inline void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{ }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)

drivers/usb/dwc3/ep0.c +2 -0

index 8b668ef..4f216bd 100644
@@ -616,6 +616,8 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 		return -EINVAL;
 
 	case USB_STATE_ADDRESS:
+		dwc3_gadget_clear_tx_fifos(dwc);
+
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
 		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

drivers/usb/dwc3/gadget.c +0 -0

index 86f257f..26f9d64 100644

drivers/usb/dwc3/gadget.c +12 -0

+
+	fifo_size = mult * ((max_packet + mdwidth) / mdwidth) + 1;
+	return fifo_size;
+}
+
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{
+	struct dwc3_ep *dep;
+	int fifo_depth;
+	int size;
+	int num;
+

drivers/usb/dwc3/gadget.c +30 -0

+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+	}
+	dwc->num_ep_resized = 0;
+}
+
+/*
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In general, FIFO depths are represented with the following equation:
+ *
+ * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+ *
+ * Conversions can be done to the equation to derive the number of packets that
+ * will fit to a particular FIFO size value.
+ */
+static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	int fifo_0_start;
+	int ram1_depth;

drivers/usb/dwc3/gadget.c +5 -0

+
+	/* resize IN endpoints except ep0 */
+	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
+		return 0;
+

drivers/usb/dwc3/gadget.c +5 -0

+	}
+
+	fifo_size += fifo;
+	/* Last increment according to the TX FIFO size equation */
+	fifo_size++;

drivers/usb/dwc3/gadget.c +15 -0

+		dwc->last_fifo_depth -= fifo_size;
+		return -ENOMEM;
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dwc->num_ep_resized++;
+
+	return 0;
+}
+
 /**
  * __dwc3_gadget_ep_enable - initializes a hw endpoint
  * @dep: endpoint to be initialized

@@ -632,6 +787,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	int			ret;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
+		ret = dwc3_gadget_resize_tx_fifos(dep);
+		if (ret)
+			return ret;
+
 		ret = dwc3_gadget_start_config(dep);
 		if (ret)
 			return ret;

@@ -2418,6 +2577,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	free_irq(dwc->irq_gadget, dwc->ev_buf);

drivers/usb/dwc3/gadget.c +33 -0

+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,

@@ -2495,6 +2688,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */

Hi,

Quoted 32 lines · Wesley Cheng

Some devices have USB compositions which may require multiple endpoints that support EP bursting. HW defined TX FIFO sizes may not always be sufficient for these compositions. By utilizing flexible TX FIFO allocation, this allows for endpoints to request the required FIFO depth to achieve higher bandwidth. With some higher bMaxBurst configurations, using a larger TX FIFO size results in better TX throughput.

By introducing the check_config() callback, the resizing logic can fetch the maximum number of endpoints used in the USB composition (can contain multiple configurations), which helps ensure that the resizing logic can fulfill the configuration(s), or return an error to the gadget layer otherwise during bind time.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |   8 ++
 drivers/usb/dwc3/ep0.c    |   2 +
 drivers/usb/dwc3/gadget.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

drivers/usb/dwc3/core.c +2 -0

index 6969196..e7fa6af 100644
@@ -1284,6 +1284,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				&tx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,tx-max-burst-prd",
 				&tx_max_burst_prd);
+	dwc->needs_fifo_resize = device_property_read_bool(dev,
+							   "tx-fifo-resize");
 

drivers/usb/dwc3/core.h struct dwc3 { · line 1226

Quoted 11 lines

drivers/usb/dwc3/core.c +0 -0

 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");

drivers/usb/dwc3/core.h +1 -0

index eec1cf4..983b2fd4 100644
@@ -1223,6 +1223,7 @@ struct dwc3 {
 	unsigned		is_utmi_l1_suspend:1;
 	unsigned		is_fpga:1;
 	unsigned		pending_events:1;
+	unsigned		needs_fifo_resize:1;

The prefix "need" sounds like a requirement, but I don't think it is the case here. I think "do" would be a better prefix here.

Quoted 6 lines

drivers/usb/dwc3/core.h +0 -0

 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;

@@ -1257,6 +1258,10 @@ struct dwc3 {
 	unsigned		dis_split_quirk:1;
 

drivers/usb/dwc3/core.h struct dwc3 { · line 1265

Quoted 6 lines

drivers/usb/dwc3/core.h +4 -0

 	u16			imod_interval;
+
+	int			max_cfg_eps;
+	int			last_fifo_depth;
+	int			num_ep_resized;
 };

Please document these new fields.

Quoted 40 lines

drivers/usb/dwc3/core.h +3 -0

 #define INCRX_BURST_MODE 0

@@ -1471,6 +1476,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 		u32 param);
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_init(struct dwc3 *dwc)
 { return 0; }

@@ -1490,6 +1496,8 @@ static inline int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 		int cmd, u32 param)
 { return 0; }
+static inline void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{ }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)

drivers/usb/dwc3/ep0.c +2 -0

index 8b668ef..4f216bd 100644
@@ -616,6 +616,8 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 		return -EINVAL;
 
 	case USB_STATE_ADDRESS:
+		dwc3_gadget_clear_tx_fifos(dwc);
+
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
 		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

drivers/usb/dwc3/gadget.c +0 -0

index 86f257f..26f9d64 100644
@@ -615,6 +615,161 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
 		bool interrupt);
 

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 618

Quoted 1 line

drivers/usb/dwc3/gadget.c +1 -0

+static int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)

Can you document what this function does?

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 620

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+{
+	int max_packet = 1024;

Maybe you can also document why you chose 1024 (e.g. applicable to Enhanced SuperSpeed only?).

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 626

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+	int fifo_size;
+	int mdwidth;
+
+	mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
+	/* MDWIDTH is represented in bits, we need it in bytes */
+	mdwidth >>= 3;

mdwidth for DWC32 requires to read hwparams6 for the upper 2 significant bits. Can we add a check for DWC32 also? You can check how we're doing it now in the current code.

Quoted 21 lines

drivers/usb/dwc3/gadget.c +21 -0

+
+	fifo_size = mult * ((max_packet + mdwidth) / mdwidth) + 1;
+	return fifo_size;
+}
+
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{
+	struct dwc3_ep *dep;
+	int fifo_depth;
+	int size;
+	int num;
+
+	if (!dwc->needs_fifo_resize)
+		return;
+
+	/* Read ep0IN related TXFIFO size */
+	dep = dwc->eps[1];
+	size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	if (DWC3_IP_IS(DWC31))
+		fifo_depth = DWC31_GTXFIFOSIZ_TXFDEP(size);
+	else

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 648

Quoted 1 line

drivers/usb/dwc3/gadget.c +1 -0

+		fifo_depth = DWC3_GTXFIFOSIZ_TXFDEP(size);

The driver handles 3 IPs. Getting the fifo depth for DWC32 is the same as DWC31. So the condition should be
if (DWC3_IP_IS(DWC3))
       fifo_depth = ...
else
      fifo_depth = ...

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 659

Quoted 11 lines

drivers/usb/dwc3/gadget.c +11 -0

+
+	dwc->last_fifo_depth = fifo_depth;
+	/* Clear existing TXFIFO for all IN eps except ep0 */
+	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM);
+	     num += 2) {
+		dep = dwc->eps[num];
+		/* Don't change TXFRAMNUM on usb31 version */
+		size = DWC3_IP_IS(DWC31) ?
+			dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1)) &
+				   DWC31_GTXFIFOSIZ_TXFRAMNUM : 0;
+

Same here. Check for DWC32.

Quoted 34 lines

drivers/usb/dwc3/gadget.c +34 -0

+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+	}
+	dwc->num_ep_resized = 0;
+}
+
+/*
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In general, FIFO depths are represented with the following equation:
+ *
+ * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+ *
+ * Conversions can be done to the equation to derive the number of packets that
+ * will fit to a particular FIFO size value.
+ */
+static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	int fifo_0_start;
+	int ram1_depth;
+	int fifo_size;
+	int min_depth;
+	int num_in_ep;
+	int remaining;

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 699

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+	int mult = 1;
+	int fifo;
+	int tmp;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;

Maybe add a condition to check for Enhanced SuperSpeed only?

Quoted 11 lines

drivers/usb/dwc3/gadget.c +11 -0

+
+	/* resize IN endpoints except ep0 */
+	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
+		return 0;
+
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+
+	if ((dep->endpoint.maxburst > 1 &&
+	     usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
+	    usb_endpoint_xfer_isoc(dep->endpoint.desc))
+		mult = 3;

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 714

Quoted 4 lines

drivers/usb/dwc3/gadget.c +4 -0

+
+	if (dep->endpoint.maxburst > 6 &&
+	    usb_endpoint_xfer_bulk(dep->endpoint.desc) && DWC3_IP_IS(DWC31))
+		mult = 6;

You checked maxburst > 1 for isoc, but not when maxburst > 6. Why? Also, "mult" is the term we usually use for isoc endpoints. Applying it to bulk is confusing here.

How did we decide on 3 and 6? Are they arbitrary?

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+
+	/* FIFO size for a single buffer */
+	fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
+
+	/* Calculate the number of remaining EPs w/o any FIFO */
+	num_in_ep = dwc->max_cfg_eps;

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 725

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+	num_in_ep -= dwc->num_ep_resized;
+
+	/* Reserve at least one FIFO for the number of IN EPs */
+	min_depth = num_in_ep * (fifo + 1);
+	remaining = ram1_depth - min_depth - dwc->last_fifo_depth;

Can "remaining" be a negative value? If so, I think it's clearer if you do remaining = max_t(int, 0, remaining);

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 737

Quoted 12 lines

drivers/usb/dwc3/gadget.c +12 -0

+
+	/*
+	 * We've already reserved 1 FIFO per EP, so check what we can fit in
+	 * addition to it.  If there is not enough remaining space, allocate
+	 * all the remaining space to the EP.
+	 */
+	fifo_size = (mult - 1) * fifo;
+	if (remaining < fifo_size) {
+		if (remaining > 0)
+			fifo_size = remaining;
+		else
+			fifo_size = 0;

Then use this condition instead:

if (remaining < fifo_size)
       fifo_size = remaining;

Quoted 9 lines

drivers/usb/dwc3/gadget.c +9 -0

+	}
+
+	fifo_size += fifo;
+	/* Last increment according to the TX FIFO size equation */
+	fifo_size++;
+
+	/* Check if TXFIFOs start at non-zero addr */
+	tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 752

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+
+	fifo_size |= (fifo_0_start + (dwc->last_fifo_depth << 16));
+	if (DWC3_IP_IS(DWC31))
+		dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+	else
+		dwc->last_fifo_depth += DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Take account of DWC32.

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 762

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check fifo size allocation doesn't exceed available RAM size. */
+	if (dwc->last_fifo_depth >= ram1_depth) {
+		dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
+			dwc->last_fifo_depth, ram1_depth,
+			dep->endpoint.name, fifo_size);
+		if (DWC3_IP_IS(DWC31))
+			fifo_size = DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+		else
+			fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Same here.

Quoted 31 lines

drivers/usb/dwc3/gadget.c +15 -0

+		dwc->last_fifo_depth -= fifo_size;
+		return -ENOMEM;
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dwc->num_ep_resized++;
+
+	return 0;
+}
+
 /**
  * __dwc3_gadget_ep_enable - initializes a hw endpoint
  * @dep: endpoint to be initialized

@@ -632,6 +787,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	int			ret;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
+		ret = dwc3_gadget_resize_tx_fifos(dep);
+		if (ret)
+			return ret;
+
 		ret = dwc3_gadget_start_config(dep);
 		if (ret)
 			return ret;

@@ -2418,6 +2577,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 

drivers/usb/dwc3/gadget.c static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA) · line 2648

Quoted 6 lines

drivers/usb/dwc3/gadget.c +1 -0

 	free_irq(dwc->irq_gadget, dwc->ev_buf);

@@ -2485,6 +2645,39 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 	return 0;
 }
 
+static int dwc3_gadget_check_config(struct usb_gadget *g, unsigned long ep_map)

What's in ep_map? Can you document more to help with the review?

Thanks,
Thinh

Quoted 43 lines

drivers/usb/dwc3/gadget.c +33 -0

+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,

@@ -2495,6 +2688,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */

Quoted 35 lines · Thinh Nguyen

Hi,

Quoted 32 lines · Wesley Cheng

Some devices have USB compositions which may require multiple endpoints that support EP bursting. HW defined TX FIFO sizes may not always be sufficient for these compositions. By utilizing flexible TX FIFO allocation, this allows for endpoints to request the required FIFO depth to achieve higher bandwidth. With some higher bMaxBurst configurations, using a larger TX FIFO size results in better TX throughput.

By introducing the check_config() callback, the resizing logic can fetch the maximum number of endpoints used in the USB composition (can contain multiple configurations), which helps ensure that the resizing logic can fulfill the configuration(s), or return an error to the gadget layer otherwise during bind time.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |   8 ++
 drivers/usb/dwc3/ep0.c    |   2 +
 drivers/usb/dwc3/gadget.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

drivers/usb/dwc3/core.c +2 -0

index 6969196..e7fa6af 100644
@@ -1284,6 +1284,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				&tx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,tx-max-burst-prd",
 				&tx_max_burst_prd);
+	dwc->needs_fifo_resize = device_property_read_bool(dev,
+							   "tx-fifo-resize");
 

Quoted 14 lines

drivers/usb/dwc3/core.h struct dwc3 { · line 1226

Quoted 11 lines

drivers/usb/dwc3/core.c +0 -0

 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");

drivers/usb/dwc3/core.h +1 -0

index eec1cf4..983b2fd4 100644
@@ -1223,6 +1223,7 @@ struct dwc3 {
 	unsigned		is_utmi_l1_suspend:1;
 	unsigned		is_fpga:1;
 	unsigned		pending_events:1;
+	unsigned		needs_fifo_resize:1;

The prefix "need" sounds like a requirement, but I don't think it is the case here. I think "do" would be a better prefix here.

Hi Thinh,

Sure, that is true, since this may be an optional flag for certain platforms.

Quoted 6 lines

Quoted 6 lines

drivers/usb/dwc3/core.h +0 -0

 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;

@@ -1257,6 +1258,10 @@ struct dwc3 {
 	unsigned		dis_split_quirk:1;
 

Quoted 8 lines

drivers/usb/dwc3/core.h struct dwc3 { · line 1265

Quoted 6 lines

drivers/usb/dwc3/core.h +4 -0

 	u16			imod_interval;
+
+	int			max_cfg_eps;
+	int			last_fifo_depth;
+	int			num_ep_resized;
 };

Please document these new fields.

Will do.

Quoted 40 lines

Quoted 40 lines

drivers/usb/dwc3/core.h +3 -0

 #define INCRX_BURST_MODE 0

@@ -1471,6 +1476,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 		u32 param);
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_init(struct dwc3 *dwc)
 { return 0; }

@@ -1490,6 +1496,8 @@ static inline int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 		int cmd, u32 param)
 { return 0; }
+static inline void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{ }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)

drivers/usb/dwc3/ep0.c +2 -0

index 8b668ef..4f216bd 100644
@@ -616,6 +616,8 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 		return -EINVAL;
 
 	case USB_STATE_ADDRESS:
+		dwc3_gadget_clear_tx_fifos(dwc);
+
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
 		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

drivers/usb/dwc3/gadget.c +0 -0

index 86f257f..26f9d64 100644
@@ -615,6 +615,161 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
 		bool interrupt);
 

Quoted 3 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 618

Quoted 1 line

drivers/usb/dwc3/gadget.c +1 -0

+static int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)

Can you document what this function does?

Will do.

Quoted 5 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 620

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+{
+	int max_packet = 1024;

Maybe you can also document why you chose 1024 (e.g. applicable to Enhanced SuperSpeed only?).

Sure. Its basically applicable for SS and isoc (hs/ss) use cases since max packet size is 1024 in both cases.

Quoted 11 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 626

Quoted 7 lines

drivers/usb/dwc3/gadget.c +6 -0

+	int fifo_size;
+	int mdwidth;
+
+	mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
+	/* MDWIDTH is represented in bits, we need it in bytes */
+	mdwidth >>= 3;

mdwidth for DWC32 requires to read hwparams6 for the upper 2 significant bits. Can we add a check for DWC32 also? You can check how we're doing it now in the current code.

Sure. I'll make sure to get the correct registers for the DWC32 case.

Quoted 20 lines

Quoted 20 lines

drivers/usb/dwc3/gadget.c +20 -0

+
+	fifo_size = mult * ((max_packet + mdwidth) / mdwidth) + 1;
+	return fifo_size;
+}
+
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{
+	struct dwc3_ep *dep;
+	int fifo_depth;
+	int size;
+	int num;
+
+	if (!dwc->needs_fifo_resize)
+		return;
+
+	/* Read ep0IN related TXFIFO size */
+	dep = dwc->eps[1];
+	size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	if (DWC3_IP_IS(DWC31))
+		fifo_depth = DWC31_GTXFIFOSIZ_TXFDEP(size);

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 648

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+	else
+		fifo_depth = DWC3_GTXFIFOSIZ_TXFDEP(size);

The driver handles 3 IPs. Getting the fifo depth for DWC32 is the same as DWC31. So the condition should be
if (DWC3_IP_IS(DWC3))
       fifo_depth = ...
else
      fifo_depth = ...

Understood.

Quoted 46 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 659

Quoted 11 lines

drivers/usb/dwc3/gadget.c +11 -0

+
+	dwc->last_fifo_depth = fifo_depth;
+	/* Clear existing TXFIFO for all IN eps except ep0 */
+	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM);
+	     num += 2) {
+		dep = dwc->eps[num];
+		/* Don't change TXFRAMNUM on usb31 version */
+		size = DWC3_IP_IS(DWC31) ?
+			dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1)) &
+				   DWC31_GTXFIFOSIZ_TXFRAMNUM : 0;
+

Same here. Check for DWC32.

Quoted 33 lines

drivers/usb/dwc3/gadget.c +33 -0

+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+	}
+	dwc->num_ep_resized = 0;
+}
+
+/*
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In general, FIFO depths are represented with the following equation:
+ *
+ * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+ *
+ * Conversions can be done to the equation to derive the number of packets that
+ * will fit to a particular FIFO size value.
+ */
+static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	int fifo_0_start;
+	int ram1_depth;
+	int fifo_size;
+	int min_depth;
+	int num_in_ep;

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 699

Quoted 7 lines

drivers/usb/dwc3/gadget.c +7 -0

+	int remaining;
+	int mult = 1;
+	int fifo;
+	int tmp;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;

Maybe add a condition to check for Enhanced SuperSpeed only?

Since this logic applies for isoc endpoints as well in high speed mode, for high bandwidth use cases, we can't limit it to SS only.

Quoted 11 lines

Quoted 11 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* resize IN endpoints except ep0 */
+	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
+		return 0;
+
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+
+	if ((dep->endpoint.maxburst > 1 &&
+	     usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
+	    usb_endpoint_xfer_isoc(dep->endpoint.desc))

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 714

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+		mult = 3;
+
+	if (dep->endpoint.maxburst > 6 &&
+	    usb_endpoint_xfer_bulk(dep->endpoint.desc) && DWC3_IP_IS(DWC31))
+		mult = 6;

You checked maxburst > 1 for isoc, but not when maxburst > 6. Why? Also, "mult" is the term we usually use for isoc endpoints. Applying it to bulk is confusing here.

Ok, let me rename it to something else that makes more sense. The isoc endpoint check was targeted for mainly high-speed high bandwidth isoc use cases, and I don't believe our results improved with a larger fifo allocation, ie 6. (refer to below)

Quoted 3 lines

How did we decide on 3 and 6? Are they arbitrary?

So actually in the databook, they have some recommendations for TXFIFO sizes to use in "Table 4-3 Device Config Parameters." It mentions that for burst capable endpoints to have a fifo size to fit at least 3 packets of maxpacket size.

There's also "Chapter 3 Cache, FIFO RAMs, and Bandwidth Requirements," which goes over a lot of optimizations that could be done based off your system's overall latency. The sizes were chosen after we ran our peak throughput and performance testing on our devices, and these values netted the best throughput while also allowing enough fifo space for our other USB endpoints. Also, there's going to be a limit on how much improvement you see with respects to increasing the fifo size, since your system will eventually be able to pull data out of the internal fifo faster than it is being filled.

Quoted 5 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+
+	/* FIFO size for a single buffer */
+	fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
+
+	/* Calculate the number of remaining EPs w/o any FIFO */

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 725

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+	num_in_ep = dwc->max_cfg_eps;
+	num_in_ep -= dwc->num_ep_resized;
+
+	/* Reserve at least one FIFO for the number of IN EPs */
+	min_depth = num_in_ep * (fifo + 1);
+	remaining = ram1_depth - min_depth - dwc->last_fifo_depth;

Can "remaining" be a negative value? If so, I think it's clearer if you do remaining = max_t(int, 0, remaining);

Sure.

Quoted 17 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 737

Quoted 12 lines

drivers/usb/dwc3/gadget.c +12 -0

+
+	/*
+	 * We've already reserved 1 FIFO per EP, so check what we can fit in
+	 * addition to it.  If there is not enough remaining space, allocate
+	 * all the remaining space to the EP.
+	 */
+	fifo_size = (mult - 1) * fifo;
+	if (remaining < fifo_size) {
+		if (remaining > 0)
+			fifo_size = remaining;
+		else
+			fifo_size = 0;

Then use this condition instead:

if (remaining < fifo_size)
       fifo_size = remaining;

Quoted 17 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+	}
+
+	fifo_size += fifo;
+	/* Last increment according to the TX FIFO size equation */
+	fifo_size++;

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 752

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check if TXFIFOs start at non-zero addr */
+	tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);
+
+	fifo_size |= (fifo_0_start + (dwc->last_fifo_depth << 16));
+	if (DWC3_IP_IS(DWC31))
+		dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+	else
+		dwc->last_fifo_depth += DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Take account of DWC32.

Got it.

Quoted 43 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 762

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check fifo size allocation doesn't exceed available RAM size. */
+	if (dwc->last_fifo_depth >= ram1_depth) {
+		dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
+			dwc->last_fifo_depth, ram1_depth,
+			dep->endpoint.name, fifo_size);
+		if (DWC3_IP_IS(DWC31))
+			fifo_size = DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+		else
+			fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Same here.

Quoted 31 lines

drivers/usb/dwc3/gadget.c +15 -0

+		dwc->last_fifo_depth -= fifo_size;
+		return -ENOMEM;
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dwc->num_ep_resized++;
+
+	return 0;
+}
+
 /**
  * __dwc3_gadget_ep_enable - initializes a hw endpoint
  * @dep: endpoint to be initialized

@@ -632,6 +787,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	int			ret;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
+		ret = dwc3_gadget_resize_tx_fifos(dep);
+		if (ret)
+			return ret;
+
 		ret = dwc3_gadget_start_config(dep);
 		if (ret)
 			return ret;

@@ -2418,6 +2577,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 

Quoted 8 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA) · line 2648

Quoted 6 lines

drivers/usb/dwc3/gadget.c +1 -0

 	free_irq(dwc->irq_gadget, dwc->ev_buf);

@@ -2485,6 +2645,39 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 	return 0;
 }
 
+static int dwc3_gadget_check_config(struct usb_gadget *g, unsigned long ep_map)

What's in ep_map? Can you document more to help with the review?

Yeah, I will add some more comments. Just to explain here briefly, this check config callback is to address the concern pointed out by Felipe where we could run out of txfifo memory while our USB composition is being enabled. This would lead to an enumerated device, with non-functioning endpoints.

The check config will be called during the function driver bind stage (before we enumerate), and ep_map carries the number of endpoints (both in and out) being used in a particular configuration. With this information, the logic will ensure that there is enough txfifo space for at least 1 fifo per endpoint. If not, we can catch the failure at the composition bind stages. (although it would be odd to see a DWC3 controller with not enough txfifo ram for 1 fifo per ep) The point at which we actually resize the fifo allocations, will always check to make sure that there is enough fifo space for the remaining endpoints after every resize.

Thanks
Wesley Cheng

Quoted 46 lines

Thanks,
Thinh

Quoted 43 lines

drivers/usb/dwc3/gadget.c +33 -0

+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,

@@ -2495,6 +2688,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */

Quoted 117 lines · Wesley Cheng

Quoted 35 lines · Thinh Nguyen

Hi,

Quoted 32 lines · Wesley Cheng

Some devices have USB compositions which may require multiple endpoints that support EP bursting. HW defined TX FIFO sizes may not always be sufficient for these compositions. By utilizing flexible TX FIFO allocation, this allows for endpoints to request the required FIFO depth to achieve higher bandwidth. With some higher bMaxBurst configurations, using a larger TX FIFO size results in better TX throughput.

By introducing the check_config() callback, the resizing logic can fetch the maximum number of endpoints used in the USB composition (can contain multiple configurations), which helps ensure that the resizing logic can fulfill the configuration(s), or return an error to the gadget layer otherwise during bind time.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |   8 ++
 drivers/usb/dwc3/ep0.c    |   2 +
 drivers/usb/dwc3/gadget.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

drivers/usb/dwc3/core.c +2 -0

index 6969196..e7fa6af 100644
@@ -1284,6 +1284,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				&tx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,tx-max-burst-prd",
 				&tx_max_burst_prd);
+	dwc->needs_fifo_resize = device_property_read_bool(dev,
+							   "tx-fifo-resize");
 

Quoted 14 lines

drivers/usb/dwc3/core.h struct dwc3 { · line 1226

Quoted 11 lines

drivers/usb/dwc3/core.c +0 -0

 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");

drivers/usb/dwc3/core.h +1 -0

index eec1cf4..983b2fd4 100644
@@ -1223,6 +1223,7 @@ struct dwc3 {
 	unsigned		is_utmi_l1_suspend:1;
 	unsigned		is_fpga:1;
 	unsigned		pending_events:1;
+	unsigned		needs_fifo_resize:1;

The prefix "need" sounds like a requirement, but I don't think it is the case here. I think "do" would be a better prefix here.

Hi Thinh,

Sure, that is true, since this may be an optional flag for certain platforms.

Quoted 6 lines

Quoted 6 lines

drivers/usb/dwc3/core.h +0 -0

 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;

@@ -1257,6 +1258,10 @@ struct dwc3 {
 	unsigned		dis_split_quirk:1;
 

Quoted 8 lines

drivers/usb/dwc3/core.h struct dwc3 { · line 1265

Quoted 6 lines

drivers/usb/dwc3/core.h +4 -0

 	u16			imod_interval;
+
+	int			max_cfg_eps;
+	int			last_fifo_depth;
+	int			num_ep_resized;
 };

Please document these new fields.

Will do.

Quoted 40 lines

Quoted 40 lines

drivers/usb/dwc3/core.h +3 -0

 #define INCRX_BURST_MODE 0

@@ -1471,6 +1476,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 		u32 param);
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_init(struct dwc3 *dwc)
 { return 0; }

@@ -1490,6 +1496,8 @@ static inline int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 		int cmd, u32 param)
 { return 0; }
+static inline void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{ }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)

drivers/usb/dwc3/ep0.c +2 -0

index 8b668ef..4f216bd 100644
@@ -616,6 +616,8 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 		return -EINVAL;
 
 	case USB_STATE_ADDRESS:
+		dwc3_gadget_clear_tx_fifos(dwc);
+
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
 		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

drivers/usb/dwc3/gadget.c +0 -0

index 86f257f..26f9d64 100644
@@ -615,6 +615,161 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
 		bool interrupt);
 

Quoted 3 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 618

Quoted 1 line

drivers/usb/dwc3/gadget.c +1 -0

+static int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)

Can you document what this function does?

Will do.

Quoted 7 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 620

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+{
+	int max_packet = 1024;

Maybe you can also document why you chose 1024 (e.g. applicable to Enhanced SuperSpeed only?).

Sure. Its basically applicable for SS and isoc (hs/ss) use cases since max packet size is 1024 in both cases.

Highspeed bulk MPS is 512. Fullspeed varies more (bulk max MPS is 64 and isoc is 1023).

However, we can keep it simple with 1024 as if it's ok to over estimate. Just need to note that here.

Quoted 99 lines

Quoted 11 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 626

Quoted 7 lines

drivers/usb/dwc3/gadget.c +6 -0

+	int fifo_size;
+	int mdwidth;
+
+	mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
+	/* MDWIDTH is represented in bits, we need it in bytes */
+	mdwidth >>= 3;

mdwidth for DWC32 requires to read hwparams6 for the upper 2 significant bits. Can we add a check for DWC32 also? You can check how we're doing it now in the current code.

Sure. I'll make sure to get the correct registers for the DWC32 case.

Quoted 20 lines

Quoted 20 lines

drivers/usb/dwc3/gadget.c +20 -0

+
+	fifo_size = mult * ((max_packet + mdwidth) / mdwidth) + 1;
+	return fifo_size;
+}
+
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{
+	struct dwc3_ep *dep;
+	int fifo_depth;
+	int size;
+	int num;
+
+	if (!dwc->needs_fifo_resize)
+		return;
+
+	/* Read ep0IN related TXFIFO size */
+	dep = dwc->eps[1];
+	size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	if (DWC3_IP_IS(DWC31))
+		fifo_depth = DWC31_GTXFIFOSIZ_TXFDEP(size);

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 648

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+	else
+		fifo_depth = DWC3_GTXFIFOSIZ_TXFDEP(size);

The driver handles 3 IPs. Getting the fifo depth for DWC32 is the same as DWC31. So the condition should be
if (DWC3_IP_IS(DWC3))
       fifo_depth = ...
else
      fifo_depth = ...

Understood.

Quoted 46 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 659

Quoted 11 lines

drivers/usb/dwc3/gadget.c +11 -0

+
+	dwc->last_fifo_depth = fifo_depth;
+	/* Clear existing TXFIFO for all IN eps except ep0 */
+	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM);
+	     num += 2) {
+		dep = dwc->eps[num];
+		/* Don't change TXFRAMNUM on usb31 version */
+		size = DWC3_IP_IS(DWC31) ?
+			dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1)) &
+				   DWC31_GTXFIFOSIZ_TXFRAMNUM : 0;
+

Same here. Check for DWC32.

Quoted 33 lines

drivers/usb/dwc3/gadget.c +33 -0

+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+	}
+	dwc->num_ep_resized = 0;
+}
+
+/*
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In general, FIFO depths are represented with the following equation:
+ *
+ * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+ *
+ * Conversions can be done to the equation to derive the number of packets that
+ * will fit to a particular FIFO size value.
+ */
+static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	int fifo_0_start;
+	int ram1_depth;
+	int fifo_size;
+	int min_depth;
+	int num_in_ep;

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 699

Quoted 7 lines

drivers/usb/dwc3/gadget.c +7 -0

+	int remaining;
+	int mult = 1;
+	int fifo;
+	int tmp;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;

Maybe add a condition to check for Enhanced SuperSpeed only?

Quoted 2 lines

Since this logic applies for isoc endpoints as well in high speed mode, for high bandwidth use cases, we can't limit it to SS only.

Ok. I was asking because you use 1024 as MPS in your calculation.

Quoted 20 lines

Quoted 11 lines

Quoted 11 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* resize IN endpoints except ep0 */
+	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
+		return 0;
+
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+
+	if ((dep->endpoint.maxburst > 1 &&
+	     usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
+	    usb_endpoint_xfer_isoc(dep->endpoint.desc))

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 714

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+		mult = 3;
+
+	if (dep->endpoint.maxburst > 6 &&
+	    usb_endpoint_xfer_bulk(dep->endpoint.desc) && DWC3_IP_IS(DWC31))
+		mult = 6;

You checked maxburst > 1 for isoc, but not when maxburst > 6. Why? Also, "mult" is the term we usually use for isoc endpoints. Applying it to bulk is confusing here.

Quoted 4 lines

Ok, let me rename it to something else that makes more sense. The isoc endpoint check was targeted for mainly high-speed high bandwidth isoc use cases, and I don't believe our results improved with a larger fifo allocation, ie 6. (refer to below)

It should improve for isoc and reduce missed isoc error also. Most applications only use 1-16KB max per interval, so you don't see the impact as much.

Quoted 8 lines

Quoted 3 lines

How did we decide on 3 and 6? Are they arbitrary?

So actually in the databook, they have some recommendations for TXFIFO sizes to use in "Table 4-3 Device Config Parameters." It mentions that for burst capable endpoints to have a fifo size to fit at least 3 packets of maxpacket size.

Quoted 9 lines

There's also "Chapter 3 Cache, FIFO RAMs, and Bandwidth Requirements," which goes over a lot of optimizations that could be done based off your system's overall latency. The sizes were chosen after we ran our peak throughput and performance testing on our devices, and these values netted the best throughput while also allowing enough fifo space for our other USB endpoints. Also, there's going to be a limit on how much improvement you see with respects to increasing the fifo size, since your system will eventually be able to pull data out of the internal fifo faster than it is being filled.

I added a patch a while back to check the max packet limit based on the recommended minimum Rx/TxFIFO size
d94ea5319813 ("usb: dwc3: gadget: Properly set maxpacket limit")

The driver wouldn't match the endpoint if it doesn't meet the minimum requirement of 3 MPS if the device is operating in SuperSpeed or SuperSpeed Plus. Was the check for "3" necessary?

"6" is your tested value right? It may be different for different setup. Can we pass this as a setting parameter from the devicetree property?

Quoted 119 lines

Quoted 5 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+
+	/* FIFO size for a single buffer */
+	fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
+
+	/* Calculate the number of remaining EPs w/o any FIFO */

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 725

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+	num_in_ep = dwc->max_cfg_eps;
+	num_in_ep -= dwc->num_ep_resized;
+
+	/* Reserve at least one FIFO for the number of IN EPs */
+	min_depth = num_in_ep * (fifo + 1);
+	remaining = ram1_depth - min_depth - dwc->last_fifo_depth;

Can "remaining" be a negative value? If so, I think it's clearer if you do remaining = max_t(int, 0, remaining);

Sure.

Quoted 17 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 737

Quoted 12 lines

drivers/usb/dwc3/gadget.c +12 -0

+
+	/*
+	 * We've already reserved 1 FIFO per EP, so check what we can fit in
+	 * addition to it.  If there is not enough remaining space, allocate
+	 * all the remaining space to the EP.
+	 */
+	fifo_size = (mult - 1) * fifo;
+	if (remaining < fifo_size) {
+		if (remaining > 0)
+			fifo_size = remaining;
+		else
+			fifo_size = 0;

Then use this condition instead:

if (remaining < fifo_size)
       fifo_size = remaining;

Quoted 17 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+	}
+
+	fifo_size += fifo;
+	/* Last increment according to the TX FIFO size equation */
+	fifo_size++;

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 752

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check if TXFIFOs start at non-zero addr */
+	tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);
+
+	fifo_size |= (fifo_0_start + (dwc->last_fifo_depth << 16));
+	if (DWC3_IP_IS(DWC31))
+		dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+	else
+		dwc->last_fifo_depth += DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Take account of DWC32.

Got it.

Quoted 43 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 762

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check fifo size allocation doesn't exceed available RAM size. */
+	if (dwc->last_fifo_depth >= ram1_depth) {
+		dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
+			dwc->last_fifo_depth, ram1_depth,
+			dep->endpoint.name, fifo_size);
+		if (DWC3_IP_IS(DWC31))
+			fifo_size = DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+		else
+			fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Same here.

Quoted 31 lines

drivers/usb/dwc3/gadget.c +15 -0

+		dwc->last_fifo_depth -= fifo_size;
+		return -ENOMEM;
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dwc->num_ep_resized++;
+
+	return 0;
+}
+
 /**
  * __dwc3_gadget_ep_enable - initializes a hw endpoint
  * @dep: endpoint to be initialized

@@ -632,6 +787,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	int			ret;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
+		ret = dwc3_gadget_resize_tx_fifos(dep);
+		if (ret)
+			return ret;
+
 		ret = dwc3_gadget_start_config(dep);
 		if (ret)
 			return ret;

@@ -2418,6 +2577,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 

Quoted 8 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA) · line 2648

Quoted 6 lines

drivers/usb/dwc3/gadget.c +1 -0

 	free_irq(dwc->irq_gadget, dwc->ev_buf);

@@ -2485,6 +2645,39 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 	return 0;
 }
 
+static int dwc3_gadget_check_config(struct usb_gadget *g, unsigned long ep_map)

What's in ep_map? Can you document more to help with the review?

Yeah, I will add some more comments. Just to explain here briefly, this check config callback is to address the concern pointed out by Felipe where we could run out of txfifo memory while our USB composition is being enabled. This would lead to an enumerated device, with non-functioning endpoints.

The check config will be called during the function driver bind stage (before we enumerate), and ep_map carries the number of endpoints (both in and out) being used in a particular configuration. With this information, the logic will ensure that there is enough txfifo space for at least 1 fifo per endpoint. If not, we can catch the failure at the composition bind stages. (although it would be odd to see a DWC3 controller with not enough txfifo ram for 1 fifo per ep) The point at which we actually resize the fifo allocations, will always check to make sure that there is enough fifo space for the remaining endpoints after every resize.

Quoted 2 lines

Thanks
Wesley Cheng

Thanks for the info. I'll review more after you add more detail.

BR,
Thinh

Quoted 46 lines

Quoted 46 lines

Thanks,
Thinh

Quoted 43 lines

drivers/usb/dwc3/gadget.c +33 -0

+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,

@@ -2495,6 +2688,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */

Quoted 275 lines · Thinh Nguyen

Quoted 116 lines · Wesley Cheng

Quoted 35 lines · Thinh Nguyen

Hi,

Quoted 32 lines · Wesley Cheng

Some devices have USB compositions which may require multiple endpoints that support EP bursting. HW defined TX FIFO sizes may not always be sufficient for these compositions. By utilizing flexible TX FIFO allocation, this allows for endpoints to request the required FIFO depth to achieve higher bandwidth. With some higher bMaxBurst configurations, using a larger TX FIFO size results in better TX throughput.

By introducing the check_config() callback, the resizing logic can fetch the maximum number of endpoints used in the USB composition (can contain multiple configurations), which helps ensure that the resizing logic can fulfill the configuration(s), or return an error to the gadget layer otherwise during bind time.

Signed-off-by Wesley Cheng <[email protected]>

---
 drivers/usb/dwc3/core.c   |   2 +
 drivers/usb/dwc3/core.h   |   8 ++
 drivers/usb/dwc3/ep0.c    |   2 +
 drivers/usb/dwc3/gadget.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 206 insertions(+)

drivers/usb/dwc3/core.c +2 -0

index 6969196..e7fa6af 100644
@@ -1284,6 +1284,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				&tx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,tx-max-burst-prd",
 				&tx_max_burst_prd);
+	dwc->needs_fifo_resize = device_property_read_bool(dev,
+							   "tx-fifo-resize");
 

Quoted 14 lines

drivers/usb/dwc3/core.h struct dwc3 { · line 1226

Quoted 11 lines

drivers/usb/dwc3/core.c +0 -0

 	dwc->disable_scramble_quirk = device_property_read_bool(dev,
 				"snps,disable_scramble_quirk");

drivers/usb/dwc3/core.h +1 -0

index eec1cf4..983b2fd4 100644
@@ -1223,6 +1223,7 @@ struct dwc3 {
 	unsigned		is_utmi_l1_suspend:1;
 	unsigned		is_fpga:1;
 	unsigned		pending_events:1;
+	unsigned		needs_fifo_resize:1;

The prefix "need" sounds like a requirement, but I don't think it is the case here. I think "do" would be a better prefix here.

Hi Thinh,

Sure, that is true, since this may be an optional flag for certain platforms.

Quoted 6 lines

Quoted 6 lines

drivers/usb/dwc3/core.h +0 -0

 	unsigned		pullups_connected:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		three_stage_setup:1;

@@ -1257,6 +1258,10 @@ struct dwc3 {
 	unsigned		dis_split_quirk:1;
 

Quoted 8 lines

drivers/usb/dwc3/core.h struct dwc3 { · line 1265

Quoted 6 lines

drivers/usb/dwc3/core.h +4 -0

 	u16			imod_interval;
+
+	int			max_cfg_eps;
+	int			last_fifo_depth;
+	int			num_ep_resized;
 };

Please document these new fields.

Will do.

Quoted 40 lines

Quoted 40 lines

drivers/usb/dwc3/core.h +3 -0

 #define INCRX_BURST_MODE 0

@@ -1471,6 +1476,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
 		u32 param);
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_init(struct dwc3 *dwc)
 { return 0; }

@@ -1490,6 +1496,8 @@ static inline int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 static inline int dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 		int cmd, u32 param)
 { return 0; }
+static inline void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{ }
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)

drivers/usb/dwc3/ep0.c +2 -0

index 8b668ef..4f216bd 100644
@@ -616,6 +616,8 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 		return -EINVAL;
 
 	case USB_STATE_ADDRESS:
+		dwc3_gadget_clear_tx_fifos(dwc);
+
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
 		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {

drivers/usb/dwc3/gadget.c +0 -0

index 86f257f..26f9d64 100644
@@ -615,6 +615,161 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
 static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
 		bool interrupt);
 

Quoted 3 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 618

Quoted 1 line

drivers/usb/dwc3/gadget.c +1 -0

+static int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)

Can you document what this function does?

Will do.

Quoted 7 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 620

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+{
+	int max_packet = 1024;

Maybe you can also document why you chose 1024 (e.g. applicable to Enhanced SuperSpeed only?).

Sure. Its basically applicable for SS and isoc (hs/ss) use cases since max packet size is 1024 in both cases.

Highspeed bulk MPS is 512. Fullspeed varies more (bulk max MPS is 64 and isoc is 1023).

However, we can keep it simple with 1024 as if it's ok to over estimate. Just need to note that here.

Quoted 98 lines

Quoted 10 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 626

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+	int fifo_size;
+	int mdwidth;
+
+	mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
+	/* MDWIDTH is represented in bits, we need it in bytes */
+	mdwidth >>= 3;

mdwidth for DWC32 requires to read hwparams6 for the upper 2 significant bits. Can we add a check for DWC32 also? You can check how we're doing it now in the current code.

Sure. I'll make sure to get the correct registers for the DWC32 case.

Quoted 20 lines

Quoted 20 lines

drivers/usb/dwc3/gadget.c +20 -0

+
+	fifo_size = mult * ((max_packet + mdwidth) / mdwidth) + 1;
+	return fifo_size;
+}
+
+void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
+{
+	struct dwc3_ep *dep;
+	int fifo_depth;
+	int size;
+	int num;
+
+	if (!dwc->needs_fifo_resize)
+		return;
+
+	/* Read ep0IN related TXFIFO size */
+	dep = dwc->eps[1];
+	size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	if (DWC3_IP_IS(DWC31))
+		fifo_depth = DWC31_GTXFIFOSIZ_TXFDEP(size);

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 648

Quoted 2 lines

drivers/usb/dwc3/gadget.c +2 -0

+	else
+		fifo_depth = DWC3_GTXFIFOSIZ_TXFDEP(size);

The driver handles 3 IPs. Getting the fifo depth for DWC32 is the same as DWC31. So the condition should be
if (DWC3_IP_IS(DWC3))
       fifo_depth = ...
else
      fifo_depth = ...

Understood.

Quoted 46 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 659

Quoted 11 lines

drivers/usb/dwc3/gadget.c +11 -0

+
+	dwc->last_fifo_depth = fifo_depth;
+	/* Clear existing TXFIFO for all IN eps except ep0 */
+	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM);
+	     num += 2) {
+		dep = dwc->eps[num];
+		/* Don't change TXFRAMNUM on usb31 version */
+		size = DWC3_IP_IS(DWC31) ?
+			dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1)) &
+				   DWC31_GTXFIFOSIZ_TXFRAMNUM : 0;
+

Same here. Check for DWC32.

Quoted 33 lines

drivers/usb/dwc3/gadget.c +33 -0

+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+	}
+	dwc->num_ep_resized = 0;
+}
+
+/*
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In general, FIFO depths are represented with the following equation:
+ *
+ * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+ *
+ * Conversions can be done to the equation to derive the number of packets that
+ * will fit to a particular FIFO size value.
+ */
+static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
+{
+	struct dwc3 *dwc = dep->dwc;
+	int fifo_0_start;
+	int ram1_depth;
+	int fifo_size;
+	int min_depth;
+	int num_in_ep;

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 699

Quoted 7 lines

drivers/usb/dwc3/gadget.c +7 -0

+	int remaining;
+	int mult = 1;
+	int fifo;
+	int tmp;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;

Maybe add a condition to check for Enhanced SuperSpeed only?

Quoted 2 lines

Since this logic applies for isoc endpoints as well in high speed mode, for high bandwidth use cases, we can't limit it to SS only.

Ok. I was asking because you use 1024 as MPS in your calculation.

Quoted 19 lines

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Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* resize IN endpoints except ep0 */
+	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
+		return 0;
+
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+
+	if ((dep->endpoint.maxburst > 1 &&
+	     usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
+	    usb_endpoint_xfer_isoc(dep->endpoint.desc))

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 714

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+		mult = 3;
+
+	if (dep->endpoint.maxburst > 6 &&
+	    usb_endpoint_xfer_bulk(dep->endpoint.desc) && DWC3_IP_IS(DWC31))
+		mult = 6;

You checked maxburst > 1 for isoc, but not when maxburst > 6. Why? Also, "mult" is the term we usually use for isoc endpoints. Applying it to bulk is confusing here.

Quoted 4 lines

Ok, let me rename it to something else that makes more sense. The isoc endpoint check was targeted for mainly high-speed high bandwidth isoc use cases, and I don't believe our results improved with a larger fifo allocation, ie 6. (refer to below)

It should improve for isoc and reduce missed isoc error also. Most applications only use 1-16KB max per interval, so you don't see the impact as much.

Quoted 7 lines

Quoted 2 lines

How did we decide on 3 and 6? Are they arbitrary?

So actually in the databook, they have some recommendations for TXFIFO sizes to use in "Table 4-3 Device Config Parameters." It mentions that for burst capable endpoints to have a fifo size to fit at least 3 packets of maxpacket size.

Quoted 9 lines

There's also "Chapter 3 Cache, FIFO RAMs, and Bandwidth Requirements," which goes over a lot of optimizations that could be done based off your system's overall latency. The sizes were chosen after we ran our peak throughput and performance testing on our devices, and these values netted the best throughput while also allowing enough fifo space for our other USB endpoints. Also, there's going to be a limit on how much improvement you see with respects to increasing the fifo size, since your system will eventually be able to pull data out of the internal fifo faster than it is being filled.

Quoted 8 lines

I added a patch a while back to check the max packet limit based on the recommended minimum Rx/TxFIFO size
d94ea5319813 ("usb: dwc3: gadget: Properly set maxpacket limit")

The driver wouldn't match the endpoint if it doesn't meet the minimum requirement of 3 MPS if the device is operating in SuperSpeed or SuperSpeed Plus. Was the check for "3" necessary?

Hi Thinh,

Please correct me if I'm wrong, but when a function driver requests for an endpoint using usb_ep_autoconfig(), most of the time it passes in a FS descriptor that doesn't have the wMaxPacketSize parameter set (0), which means it will probably fetch the first unused endpoint. (at least this is what I noticed for the BULK ep cases)

In this case, it would be hard to determine if the endpoint selected would already have the constraint you added factored in.

Quoted 3 lines

"6" is your tested value right? It may be different for different setup. Can we pass this as a setting parameter from the devicetree property?

Definitely can agree to that. We can make things a bit more flexible depending on the system. Maybe create a new property, and default it to 6 if "do_fifo_resize" is set, but this parameter is not defined.

Thanks
Wesley Cheng

Quoted 172 lines

Quoted 119 lines

Quoted 5 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+
+	/* FIFO size for a single buffer */
+	fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
+
+	/* Calculate the number of remaining EPs w/o any FIFO */

Quoted 9 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 725

Quoted 6 lines

drivers/usb/dwc3/gadget.c +6 -0

+	num_in_ep = dwc->max_cfg_eps;
+	num_in_ep -= dwc->num_ep_resized;
+
+	/* Reserve at least one FIFO for the number of IN EPs */
+	min_depth = num_in_ep * (fifo + 1);
+	remaining = ram1_depth - min_depth - dwc->last_fifo_depth;

Can "remaining" be a negative value? If so, I think it's clearer if you do remaining = max_t(int, 0, remaining);

Sure.

Quoted 17 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 737

Quoted 12 lines

drivers/usb/dwc3/gadget.c +12 -0

+
+	/*
+	 * We've already reserved 1 FIFO per EP, so check what we can fit in
+	 * addition to it.  If there is not enough remaining space, allocate
+	 * all the remaining space to the EP.
+	 */
+	fifo_size = (mult - 1) * fifo;
+	if (remaining < fifo_size) {
+		if (remaining > 0)
+			fifo_size = remaining;
+		else
+			fifo_size = 0;

Then use this condition instead:

if (remaining < fifo_size)
       fifo_size = remaining;

Quoted 17 lines

Quoted 5 lines

drivers/usb/dwc3/gadget.c +5 -0

+	}
+
+	fifo_size += fifo;
+	/* Last increment according to the TX FIFO size equation */
+	fifo_size++;

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 752

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check if TXFIFOs start at non-zero addr */
+	tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+	fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);
+
+	fifo_size |= (fifo_0_start + (dwc->last_fifo_depth << 16));
+	if (DWC3_IP_IS(DWC31))
+		dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+	else
+		dwc->last_fifo_depth += DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Take account of DWC32.

Got it.

Quoted 43 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action) · line 762

Quoted 10 lines

drivers/usb/dwc3/gadget.c +10 -0

+
+	/* Check fifo size allocation doesn't exceed available RAM size. */
+	if (dwc->last_fifo_depth >= ram1_depth) {
+		dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
+			dwc->last_fifo_depth, ram1_depth,
+			dep->endpoint.name, fifo_size);
+		if (DWC3_IP_IS(DWC31))
+			fifo_size = DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
+		else
+			fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);

Same here.

Quoted 31 lines

drivers/usb/dwc3/gadget.c +15 -0

+		dwc->last_fifo_depth -= fifo_size;
+		return -ENOMEM;
+	}
+
+	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dwc->num_ep_resized++;
+
+	return 0;
+}
+
 /**
  * __dwc3_gadget_ep_enable - initializes a hw endpoint
  * @dep: endpoint to be initialized

@@ -632,6 +787,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	int			ret;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
+		ret = dwc3_gadget_resize_tx_fifos(dep);
+		if (ret)
+			return ret;
+
 		ret = dwc3_gadget_start_config(dep);
 		if (ret)
 			return ret;

@@ -2418,6 +2577,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 

Quoted 8 lines

drivers/usb/dwc3/gadget.c static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA) · line 2648

Quoted 6 lines

drivers/usb/dwc3/gadget.c +1 -0

 	free_irq(dwc->irq_gadget, dwc->ev_buf);

@@ -2485,6 +2645,39 @@ static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
 	return 0;
 }
 
+static int dwc3_gadget_check_config(struct usb_gadget *g, unsigned long ep_map)

What's in ep_map? Can you document more to help with the review?

Yeah, I will add some more comments. Just to explain here briefly, this check config callback is to address the concern pointed out by Felipe where we could run out of txfifo memory while our USB composition is being enabled. This would lead to an enumerated device, with non-functioning endpoints.

The check config will be called during the function driver bind stage (before we enumerate), and ep_map carries the number of endpoints (both in and out) being used in a particular configuration. With this information, the logic will ensure that there is enough txfifo space for at least 1 fifo per endpoint. If not, we can catch the failure at the composition bind stages. (although it would be odd to see a DWC3 controller with not enough txfifo ram for 1 fifo per ep) The point at which we actually resize the fifo allocations, will always check to make sure that there is enough fifo space for the remaining endpoints after every resize.

Quoted 2 lines

Thanks
Wesley Cheng

Thanks for the info. I'll review more after you add more detail.

BR,
Thinh

Quoted 46 lines

Quoted 46 lines

Thanks,
Thinh

Quoted 43 lines

drivers/usb/dwc3/gadget.c +33 -0

+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,

@@ -2495,6 +2688,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
 	.vbus_draw		= dwc3_gadget_vbus_draw,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */