Hi Rob, On 12/18/2018 8:41 AM, Rob Herring wrote: > On Fri, Dec 07, 2018 at 06:27:43PM -0800, Thinh Nguyen wrote: >> 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 <thinhn@xxxxxxxxxxxx> >> --- >> 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(+) >> >> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt >> index b7e67edff9b2..01b948fff0eb 100644 >> --- a/Documentation/devicetree/bindings/usb/dwc3.txt >> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt >> @@ -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. Can you clarify further how that will work? (I think I may misunderstand what you mean) Thanks for the review! Thinh
