Re: [PATCH v2 3/4] usb: dwc3: Add property snps,enable-refclk-sof

[Rob Herring <robh@kernel.org>]

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@synopsys.com>
> ---
> 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.

>  
>   - <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be reallocated.
>   - snps,incr-burst-type-adjustment: Value for INCR burst type of GSBUSCFG0
> -- 
> 2.11.0
>