usb: dwc3: Introduce refclk lpm

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt +0 -0

index 8e5265e9f658..b7e67edff9b2 100644

Quoted 18 lines · Thinh Nguyen

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 10 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

index 8e5265e9f658..b7e67edff9b2 100644
@@ -99,6 +99,8 @@ Optional properties:
 			this and tx-thr-num-pkt-prd to a valid, non-zero value
 			1-16 (DWC_usb31 programming guide section 1.2.3) to
 			enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+			reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

Hi Rob,

Quoted 19 lines · Rob Herring

Quoted 18 lines · Thinh Nguyen

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Quoted 12 lines

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 10 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

index 8e5265e9f658..b7e67edff9b2 100644
@@ -99,6 +99,8 @@ Optional properties:
                     this and tx-thr-num-pkt-prd to a valid, non-zero value
                     1-16 (DWC_usb31 programming guide section 1.2.3) to
                     enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+                    reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

The thing is we cannot determine the ref_clk frequency for some devices that don't specify their clocks. So I think we should have an option to inform the controller of the ref_clk period for those devices.

Quoted 34 lines · Thinh Nguyen

Hi Rob,

Quoted 31 lines · Rob Herring

Quoted 23 lines · Thinh Nguyen

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt +0 -0

index 8e5265e9f658..b7e67edff9b2 100644

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 5 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

@@ -99,6 +99,8 @@ Optional properties:
                     this and tx-thr-num-pkt-prd to a valid, non-zero value
                     1-16 (DWC_usb31 programming guide section 1.2.3) to
                     enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+                    reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

Quoted 3 lines

The thing is we cannot determine the ref_clk frequency for some devices that don't specify their clocks. So I think we should have an option to inform the controller of the ref_clk period for those devices.

Specifying the clock should be mandatory (if you want/need this feature). It just requires a fixed-clock node at a minimum.

Quoted 35 lines

Quoted 35 lines · Rob Herring

Quoted 19 lines · Thinh Nguyen

Quoted 18 lines

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Quoted 12 lines

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 10 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

index 8e5265e9f658..b7e67edff9b2 100644
@@ -99,6 +99,8 @@ Optional properties:
                     this and tx-thr-num-pkt-prd to a valid, non-zero value
                     1-16 (DWC_usb31 programming guide section 1.2.3) to
                     enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+                    reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

The thing is we cannot determine the ref_clk frequency for some devices that don't specify their clocks. So I think we should have an option to inform the controller of the ref_clk period for those devices.

Quoted 2 lines

Specifying the clock should be mandatory (if you want/need this feature). It just requires a fixed-clock node at a minimum.

Depending on the design of the controller, the ref_clk frequency is not something that the OS can read/control. So we cannot make it mandatory for every device to have a clock node.

Hi,

Quoted 35 lines · Thinh Nguyen

Quoted 35 lines

Quoted 35 lines · Rob Herring

Quoted 19 lines · Thinh Nguyen

Quoted 18 lines

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Quoted 12 lines

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 10 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

index 8e5265e9f658..b7e67edff9b2 100644
@@ -99,6 +99,8 @@ Optional properties:
                     this and tx-thr-num-pkt-prd to a valid, non-zero value
                     1-16 (DWC_usb31 programming guide section 1.2.3) to
                     enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+                    reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

The thing is we cannot determine the ref_clk frequency for some devices that don't specify their clocks. So I think we should have an option to inform the controller of the ref_clk period for those devices.

Quoted 5 lines

Quoted 2 lines

Specifying the clock should be mandatory (if you want/need this feature). It just requires a fixed-clock node at a minimum.

Depending on the design of the controller, the ref_clk frequency is not something that the OS can read/control. So we cannot make it mandatory for every device to have a clock node.

We can make it mandatory to everyone who wants to use the feature. It's no different than making snps,refclk-period-ns mandatory to everyone who wants to use the feature you're introducing.

Hi,

Quoted 43 lines · Felipe Balbi

Hi,

Quoted 40 lines · Thinh Nguyen

Quoted 32 lines

Quoted 32 lines · Rob Herring

Quoted 31 lines · Thinh Nguyen

Quoted 23 lines

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt +0 -0

index 8e5265e9f658..b7e67edff9b2 100644

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 5 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

@@ -99,6 +99,8 @@ Optional properties:
                     this and tx-thr-num-pkt-prd to a valid, non-zero value
                     1-16 (DWC_usb31 programming guide section 1.2.3) to
                     enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+                    reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

Quoted 5 lines

Quoted 3 lines

The thing is we cannot determine the ref_clk frequency for some devices that don't specify their clocks. So I think we should have an option to inform the controller of the ref_clk period for those devices.

Specifying the clock should be mandatory (if you want/need this feature). It just requires a fixed-clock node at a minimum.

Depending on the design of the controller, the ref_clk frequency is not something that the OS can read/control. So we cannot make it mandatory for every device to have a clock node.

Quoted 4 lines

We can make it mandatory to everyone who wants to use the feature. It's no different than making snps,refclk-period-ns mandatory to everyone who wants to use the feature you're introducing.

But not every design has access to the clock with an actual address for the OS to read. Only the developers will know the frequency of the ref_clk, and they can inform the controller via this property.

Quoted 46 lines · Thinh Nguyen

Hi,

Quoted 43 lines · Felipe Balbi

Hi,

Quoted 40 lines · Thinh Nguyen

Quoted 32 lines

Quoted 32 lines · Rob Herring

Quoted 31 lines · Thinh Nguyen

Quoted 23 lines

This patch introduces property "snps,refclk-period-ns" to inform the controller of the reference clock period. If the reference clock period is different from the default Core Consultant setting, then this property can be set to the reference clock period.

This property does not control the reference clock rate. The controller uses this value to perform internal timing calculations that are based on the reference clock.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Split from "usb: dwc3: Add reference clock properties"
- Revise commit message and property description

 Documentation/devicetree/bindings/usb/dwc3.txt | 2 ++
 1 file changed, 2 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt +0 -0

index 8e5265e9f658..b7e67edff9b2 100644

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 103

Quoted 5 lines

Documentation/devicetree/bindings/usb/dwc3.txt +2 -0

@@ -99,6 +99,8 @@ Optional properties:
                     this and tx-thr-num-pkt-prd to a valid, non-zero value
                     1-16 (DWC_usb31 programming guide section 1.2.3) to
                     enable periodic ESS TX threshold.
+ - snps,refclk-period-ns: if set, this value informs the controller of the
+                    reference clock period in nanoseconds.

Shouldn't you be able to retrieve the refclk frequency and then calculate the period?

Quoted 5 lines

Quoted 3 lines

The thing is we cannot determine the ref_clk frequency for some devices that don't specify their clocks. So I think we should have an option to inform the controller of the ref_clk period for those devices.

Specifying the clock should be mandatory (if you want/need this feature). It just requires a fixed-clock node at a minimum.

Depending on the design of the controller, the ref_clk frequency is not something that the OS can read/control. So we cannot make it mandatory for every device to have a clock node.

Quoted 7 lines

Quoted 4 lines

We can make it mandatory to everyone who wants to use the feature. It's no different than making snps,refclk-period-ns mandatory to everyone who wants to use the feature you're introducing.

But not every design has access to the clock with an actual address for the OS to read. Only the developers will know the frequency of the ref_clk, and they can inform the controller via this property.

Then you use the flxed-clock binding.

This patch adds a property to enable the controller to track the frame number based on the reference clock.

When operating in USB 2.0 mode, the peripheral controller uses the USB2 PHY clocks to track the frame number. This prevents the controller from suspending the USB2 PHY when the device goes into low power. Version 1.80a of the DWC_usb31 peripheral controller introduces a way to track frame number based on the reference clock instead. This feature allows the controller to suspend the USB2 PHY when the device goes into low power. This improves power saving for devices that have isochronous endpoints.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Revise property description
- Rename property from snps,enable-refclk-lpm to snps,enable-refclk-sof

 Documentation/devicetree/bindings/usb/dwc3.txt | 3 +++
 1 file changed, 3 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt +0 -0

index b7e67edff9b2..01b948fff0eb 100644

Documentation/devicetree/bindings/usb/dwc3.txt +0 -0

  - <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be reallocated.
  - snps,incr-burst-type-adjustment: Value for INCR burst type of GSBUSCFG0

Signature · 1 line

2.11.0

Quoted 21 lines · Thinh Nguyen

This patch adds a property to enable the controller to track the frame number based on the reference clock.

When operating in USB 2.0 mode, the peripheral controller uses the USB2 PHY clocks to track the frame number. This prevents the controller from suspending the USB2 PHY when the device goes into low power. Version 1.80a of the DWC_usb31 peripheral controller introduces a way to track frame number based on the reference clock instead. This feature allows the controller to suspend the USB2 PHY when the device goes into low power. This improves power saving for devices that have isochronous endpoints.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Revise property description
- Rename property from snps,enable-refclk-lpm to snps,enable-refclk-sof

 Documentation/devicetree/bindings/usb/dwc3.txt | 3 +++
 1 file changed, 3 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 106

Quoted 11 lines

Documentation/devicetree/bindings/usb/dwc3.txt +3 -0

index b7e67edff9b2..01b948fff0eb 100644
@@ -101,6 +101,9 @@ Optional properties:
 			enable periodic ESS TX threshold.
  - snps,refclk-period-ns: if set, this value informs the controller of the
 			reference clock period in nanoseconds.
+ - snps,enable-refclk-sof: set to enable reference clock based frame number
+			tracking while in low power, allowing the controller to
+			suspend the PHY during low power states.

This should be implied by the compatible string.

Quoted 21 lines · Thinh Nguyen

This patch adds a property to enable the controller to track the frame number based on the reference clock.

When operating in USB 2.0 mode, the peripheral controller uses the USB2 PHY clocks to track the frame number. This prevents the controller from suspending the USB2 PHY when the device goes into low power. Version 1.80a of the DWC_usb31 peripheral controller introduces a way to track frame number based on the reference clock instead. This feature allows the controller to suspend the USB2 PHY when the device goes into low power. This improves power saving for devices that have isochronous endpoints.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Revise property description
- Rename property from snps,enable-refclk-lpm to snps,enable-refclk-sof

 Documentation/devicetree/bindings/usb/dwc3.txt | 3 +++
 1 file changed, 3 insertions(+)

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 106

Quoted 11 lines

Documentation/devicetree/bindings/usb/dwc3.txt +3 -0

index b7e67edff9b2..01b948fff0eb 100644
@@ -101,6 +101,9 @@ Optional properties:
 			enable periodic ESS TX threshold.
  - snps,refclk-period-ns: if set, this value informs the controller of the
 			reference clock period in nanoseconds.
+ - snps,enable-refclk-sof: set to enable reference clock based frame number
+			tracking while in low power, allowing the controller to
+			suspend the PHY during low power states.

This should be implied by the compatible string.

Hi,

Quoted 22 lines · Rob Herring

Quoted 21 lines · Thinh Nguyen

This patch adds a property to enable the controller to track the frame number based on the reference clock.

When operating in USB 2.0 mode, the peripheral controller uses the USB2 PHY clocks to track the frame number. This prevents the controller from suspending the USB2 PHY when the device goes into low power. Version 1.80a of the DWC_usb31 peripheral controller introduces a way to track frame number based on the reference clock instead. This feature allows the controller to suspend the USB2 PHY when the device goes into low power. This improves power saving for devices that have isochronous endpoints.

Signed-off-by Thinh Nguyen <[email protected]>

---
Changes in v2:
- Revise property description
- Rename property from snps,enable-refclk-lpm to snps,enable-refclk-sof

 Documentation/devicetree/bindings/usb/dwc3.txt | 3 +++
 1 file changed, 3 insertions(+)

Quoted 13 lines

Documentation/devicetree/bindings/usb/dwc3.txt Optional properties: · line 106

Quoted 11 lines

Documentation/devicetree/bindings/usb/dwc3.txt +3 -0

index b7e67edff9b2..01b948fff0eb 100644
@@ -101,6 +101,9 @@ Optional properties:
                     enable periodic ESS TX threshold.
  - snps,refclk-period-ns: if set, this value informs the controller of the
                     reference clock period in nanoseconds.
+ - snps,enable-refclk-sof: set to enable reference clock based frame number
+                    tracking while in low power, allowing the controller to
+                    suspend the PHY during low power states.

This should be implied by the compatible string.

Two problems with this:

1) Won't work for PCI-based systems

2) If we start having many users of this we will end up with:

        if (of_device_is_compatible("a") ||
                of_device_is_compatible("b") ||
                of_device_is_compatible("c") ||
                of_device_is_compatible("d") ||
                ...)
                foo();

Conversely, if we just pass a flag, this branch will never change. We won't need changes to the kernel because a new platform needing refclk based frame number tracking is, now, supported upstream.