Re: [PATCH] usb: dwc2: drd: fix clock gating on USB role switch

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Sep 03, 2024 at 11:41:56AM +0200, Tomas Marek wrote:
> The dwc2_handle_usb_suspend_intr() function disables gadget clocks in USB
> peripheral mode when no other power-down mode is available (introduced by
> commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")).
> However, the dwc2_drd_role_sw_set() USB role update handler attempts to
> read DWC2 registers if the USB role has changed while the USB is in suspend
> mode (when the clocks are gated). This causes the system to hang.
> 
> Release gadget clocks before handling the USB role update.
> 
> Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")
> 
> Signed-off-by: Tomas Marek <tomas.marek@elrest.cz>
> ---
>  drivers/usb/dwc2/drd.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c
> index a8605b02115b..ccb33cd1f04b 100644
> --- a/drivers/usb/dwc2/drd.c
> +++ b/drivers/usb/dwc2/drd.c
> @@ -127,6 +127,18 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
>  			role = USB_ROLE_DEVICE;
>  	}
>  
> +#if IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \
> +	IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
> +	if (dwc2_is_device_mode(hsotg)) {
> +		if (hsotg->lx_state == DWC2_L2) {
> +			if (hsotg->params.power_down ==
> +			    DWC2_POWER_DOWN_PARAM_NONE && hsotg->bus_suspended &&
> +			    !hsotg->params.no_clock_gating)
> +				dwc2_gadget_exit_clock_gating(hsotg, 0);
> +		}
> +	}
> +#endif
> +
>  	if (role == USB_ROLE_HOST) {
>  		already = dwc2_ovr_avalid(hsotg, true);
>  	} else if (role == USB_ROLE_DEVICE) {
> -- 
> 2.25.1
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
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If you wish to discuss this problem further, or you have questions about
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thanks,

greg k-h's patch email bot