usb: gadget: Add support for disabling U1 and U2 entries

Hi

Will just vote for this feature, as I will also be able to use it for solving Rob Webers and my issue [1]

Just today I was making another solution for this feature, using the configfs instead of the devicetree. Though thinks your solution is better, as it uses the U1DevExitLat and U2DevExitLat instead. I just added my solution to the bottem of the mail for reference.

[1] https://www.spinics.net/lists/linux-usb/msg179393.html
---

From 798ea2f5f365ecdf2dbcf436a2a0302e208c6c73 Mon Sep 17 00:00:00 2001
From: "Claus H. Stovgaard" <[email protected]>
Date: Thu, 2 May 2019 17:54:45 +0200
Subject: [PATCH] usb: gadget: configfs: Add lpm_Ux_disable

When combining dwc3 with an redriver for a USB Type-C device solution, it
sometimes have problems with leaving U1/U2 for certain hosts, resulting in
link training errors and reconnects. This patch create an interface via configfs for disabling U1/U2, enabling a workaround for devices based on
dwc3.

---
 drivers/usb/dwc3/ep0.c        |  9 ++++++-
 drivers/usb/gadget/configfs.c | 56
+++++++++++++++++++++++++++++++++++++++++++
 include/linux/usb/gadget.h    |  6 ++++-
 3 files changed, 69 insertions(+), 2 deletions(-)

*
* Devices are disabled till a gadget driver successfully bind()s,
which
* means the driver will handle setup() requests needed to enumerate
(and
@@ -684,6 +686,8 @@ struct usb_gadget_driver {
char *udc_name;
struct list_head pending;
unsigned match_existing_only:1;
+ unsigned lpm_U1_disable:1;
+ unsigned lpm_U2_disable:1;
};

index 8efde17..5b2d26b 100644
@@ -379,6 +379,8 @@ static int dwc3_ep0_handle_u1(struct dwc3 *dwc,

enum usb_device_state state,
if ((dwc->speed != DWC3_DSTS_SUPERSPEED) &&
(dwc->speed != DWC3_DSTS_SUPERSPEED_PLUS))
return -EINVAL;
+ if (dwc->gadget_driver->lpm_U1_disable)
+ return -EINVAL;

reg = dwc3_readl(dwc->regs, DWC3_DCTL);
if (set)
@@ -401,6 +403,8 @@ static int dwc3_ep0_handle_u2(struct dwc3 *dwc, enum usb_device_state state,
if ((dwc->speed != DWC3_DSTS_SUPERSPEED) &&
(dwc->speed != DWC3_DSTS_SUPERSPEED_PLUS))
return -EINVAL;
+ if (dwc->gadget_driver->lpm_U2_disable)
+ return -EINVAL;

reg = dwc3_readl(dwc->regs, DWC3_DCTL);
if (set)
@@ -626,7 +630,10 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
* nothing is pending from application. */
reg = dwc3_readl(dwc->regs, DWC3_DCTL);
- reg |= (DWC3_DCTL_ACCEPTU1ENA |
DWC3_DCTL_ACCEPTU2ENA);
+ if (!dwc->gadget_driver->lpm_U1_disable)
+ reg |= DWC3_DCTL_ACCEPTU1ENA;
+ if (!dwc->gadget_driver->lpm_U2_disable)
+ reg |= DWC3_DCTL_ACCEPTU2ENA;
dwc3_writel(dwc->regs, DWC3_DCTL, reg);
}
break;

b/drivers/usb/gadget/configfs.c
index 0251299..2ee9d10 100644

@@ -229,6 +229,56 @@ static ssize_t gadget_dev_desc_bcdUSB_store(struct

config_item *item,
return len;
}

+static ssize_t gadget_dev_desc_lpm_U1_disable_show(struct config_item *item,
+ char *page)
+{
+ struct gadget_info *gi = to_gadget_info(item);
+
+ return sprintf(page, "%d\n",
+ gi->composite.gadget_driver.lpm_U1_disable);
+}
+
+static ssize_t gadget_dev_desc_lpm_U1_disable_store(struct config_item *item,
+ const char *page, size_t len)
+{
+ struct gadget_info *gi = to_gadget_info(item);
+ bool disable;
+ int ret;
+
+ ret = strtobool(page, &disable);
+ if (!ret) {
+ gi->composite.gadget_driver.lpm_U1_disable = disable;
+ ret = len;
+ }
+
+ return ret;
+}
+
+static ssize_t gadget_dev_desc_lpm_U2_disable_show(struct config_item *item,
+ char *page)
+{
+ struct gadget_info *gi = to_gadget_info(item);
+
+ return sprintf(page, "%d\n",
+ gi->composite.gadget_driver.lpm_U2_disable);
+}
+
+static ssize_t gadget_dev_desc_lpm_U2_disable_store(struct config_item *item,
+ const char *page, size_t len)
+{
+ struct gadget_info *gi = to_gadget_info(item);
+ bool disable;
+ int ret;
+
+ ret = strtobool(page, &disable);
+ if (!ret) {
+ gi->composite.gadget_driver.lpm_U2_disable = disable;
+ ret = len;
+ }
+
+ return ret;
+}
+
static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char
*page)
{
char *udc_name = to_gadget_info(item)-

@@ -299,6 +349,8 @@ CONFIGFS_ATTR(gadget_dev_desc_, idVendor);
CONFIGFS_ATTR(gadget_dev_desc_, idProduct); CONFIGFS_ATTR(gadget_dev_desc_, bcdDevice); CONFIGFS_ATTR(gadget_dev_desc_, bcdUSB);
+CONFIGFS_ATTR(gadget_dev_desc_, lpm_U1_disable); +CONFIGFS_ATTR(gadget_dev_desc_, lpm_U2_disable);
CONFIGFS_ATTR(gadget_dev_desc_, UDC);

static struct configfs_attribute *gadget_root_attrs[] = {
@@ -310,6 +362,8 @@ static struct configfs_attribute *gadget_root_attrs[] = {
&gadget_dev_desc_attr_idProduct, &gadget_dev_desc_attr_bcdDevice, &gadget_dev_desc_attr_bcdUSB,
+ &gadget_dev_desc_attr_lpm_U1_disable,
+ &gadget_dev_desc_attr_lpm_U2_disable,
&gadget_dev_desc_attr_UDC,
NULL,
};
@@ -1408,6 +1462,8 @@ static const struct usb_gadget_driver configfs_driver_template = {
.name = "configfs-gadget",
},
.match_existing_only = 1,
+ .lpm_U1_disable = 0,
+ .lpm_U2_disable = 0,
};

static struct config_group *gadgets_make(

index 7595056..25fe72b 100644
@@ -619,7 +619,9 @@ static inline int usb_gadget_activate(struct

usb_gadget *gadget)
* this driver will be bound to any available UDC.
* @pending: UDC core private data used for deferred probe of this
driver.
* @match_existing_only: If udc is not found, return an error and
don't add this
- * gadget driver to list of pending driver
+ * gadget driver to list of pending driver.
+ * @lpm_U1_disable: Instruct the UDC to disable U1 if possible.
+ * @lpm_U2_disable: Instruct the UDC to disable U2 if possible.