Re: [RFC PATCH 1/1] usb: dwc3: qcom: Keep wakeup option default off

[Krishna Kurapati]

On 11/3/2026 11:44 AM, Peter Chen wrote:
> The "wakeup-source" property, as described in
> Documentation/devicetree/bindings/power/wakeup-source.txt, only says
> that a device is capable of waking up the system. Whether wakeup is
> actually enabled is a policy decision, and drivers use
> device_may_wakeup() to decide whether to arm the hardware wakeup logic.
>
> Currently dwc3-qcom calls device_init_wakeup(dev, true) when the
> property is present, so USB wakeup is enabled by default and users who
> do not want USB activity (e.g. connect/disconnect) to wake up the system
> may have to disable it through power/wakeup, otherwise, unexpected wakeup
> may happen.
>
> Having wakeup enabled by default also costs power. In host mode,
> when device_may_wakeup() is true, system suspend keeps the controller
> and PHYs powered (dwc3_core_exit() is skipped and the genpd is not
> powered off) so that the wakeup interrupts can fire, even on systems
> where USB is never used as a wakeup source and could be fully powered
> off.
>
> For USB controllers, keep the wakeup option default off and only mark
> the device as wakeup capable, so that the user decides which USB port
> is used as a system wakeup source. Users who need it can enable it with:
>
>    echo enabled > /sys/devices/.../<dwc3 device>/power/wakeup
>
> While at it, drop the local wakeup_source variable and use
> device_property_read_bool() like the other property reads in probe.

++cros-qcom-dts-watchers since this is used in chromium userspace and 
modifications might be needed there as well.

Regards,
Krishna,

> Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxxxxxxxx>
> ---
>   drivers/usb/dwc3/dwc3-qcom.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 8116dc94c181..1451b5eaccce 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -653,7 +653,6 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>   	struct resource		*r;
>   	int			ret;
>   	bool			ignore_pipe_clk;
> -	bool			wakeup_source;
>   
>   	qcom = devm_kzalloc(&pdev->dev, sizeof(*qcom), GFP_KERNEL);
>   	if (!qcom)
> @@ -757,8 +756,8 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto remove_core;
>   
> -	wakeup_source = of_property_read_bool(dev->of_node, "wakeup-source");
> -	device_init_wakeup(&pdev->dev, wakeup_source);
> +	if (device_property_read_bool(dev, "wakeup-source"))
> +		device_set_wakeup_capable(dev, true);
>   
>   	qcom->is_suspended = false;
>