Re: [PATCH] usb: dwc3: Remove WARN_ON for device endpoint command timeouts

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Mon, Aug 04, 2025, Selvarasu Ganesan wrote:
> From: Akash M <akash.m5@samsung.com>
> 
> This commit addresses a rarely observed endpoint command timeout
> which causes kernel panic due to warn when 'panic_on_warn' is enabled
> and unnecessary call trace prints when 'panic_on_warn' is disabled.
> It is seen during fast software-controlled connect/disconnect testcases.
> The following is one such endpoint command timeout that we observed:
> 
> 1. Connect
>    =======
> ->dwc3_thread_interrupt
>  ->dwc3_ep0_interrupt
>   ->configfs_composite_setup
>    ->composite_setup
>     ->usb_ep_queue
>      ->dwc3_gadget_ep0_queue
>       ->__dwc3_gadget_ep0_queue
>        ->__dwc3_ep0_do_control_data
>         ->dwc3_send_gadget_ep_cmd
> 
> 2. Disconnect
>    ==========
> ->dwc3_thread_interrupt
>  ->dwc3_gadget_disconnect_interrupt
>   ->dwc3_ep0_reset_state
>    ->dwc3_ep0_end_control_data
>     ->dwc3_send_gadget_ep_cmd
> 
> In the issue scenario, in Exynos platforms, we observed that control
> transfers for the previous connect have not yet been completed and end
> transfer command sent as a part of the disconnect sequence and
> processing of USB_ENDPOINT_HALT feature request from the host timeout.
> This maybe an expected scenario since the controller is processing EP
> commands sent as a part of the previous connect. It maybe better to
> remove WARN_ON in all places where device endpoint commands are sent to
> avoid unnecessary kernel panic due to warn.
> 
> Fixes: e192cc7b5239 ("usb: dwc3: gadget: move cmd_endtransfer to extra function")
> Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
> Fixes: c7fcdeb2627c ("usb: dwc3: ep0: simplify EP0 state machine")
> Fixes: f0f2b2a2db85 ("usb: dwc3: ep0: push ep0state into xfernotready processing")
> Fixes: 2e3db064855a ("usb: dwc3: ep0: drop XferNotReady(DATA) support")
> Cc: stable@vger.kernel.org

I don't think this is a fix patch. You're just replacing WARN* with
dev_warn* without doing any recovery. Let's remove the Fixes and table
tag. Also, can we replace dev_warn* with dev_err* because these are
critical errors that may put the controller in a bad state.

Thanks,
Thinh

> Signed-off-by: Akash M <akash.m5@samsung.com>
> Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>

> 
> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> index 666ac432f52d..7b313836f62b 100644
> --- a/drivers/usb/dwc3/ep0.c
> +++ b/drivers/usb/dwc3/ep0.c
> @@ -288,7 +288,9 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
>  	dwc3_ep0_prepare_one_trb(dep, dwc->ep0_trb_addr, 8,
>  			DWC3_TRBCTL_CONTROL_SETUP, false);
>  	ret = dwc3_ep0_start_trans(dep);
> -	WARN_ON(ret < 0);
> +	if (ret < 0)
> +		dev_warn(dwc->dev, "ep0 out start transfer failed: %d\n", ret);
> +
>  	for (i = 2; i < DWC3_ENDPOINTS_NUM; i++) {
>  		struct dwc3_ep *dwc3_ep;
>  
> @@ -1061,7 +1063,9 @@ static void __dwc3_ep0_do_control_data(struct dwc3 *dwc,
>  		ret = dwc3_ep0_start_trans(dep);
>  	}
>  
> -	WARN_ON(ret < 0);
> +	if (ret < 0)
> +		dev_warn(dwc->dev, "ep0 data phase start transfer failed: %d\n",
> +				ret);
>  }
>  
>  static int dwc3_ep0_start_control_status(struct dwc3_ep *dep)
> @@ -1078,7 +1082,12 @@ static int dwc3_ep0_start_control_status(struct dwc3_ep *dep)
>  
>  static void __dwc3_ep0_do_control_status(struct dwc3 *dwc, struct dwc3_ep *dep)
>  {
> -	WARN_ON(dwc3_ep0_start_control_status(dep));
> +	int	ret;
> +
> +	ret = dwc3_ep0_start_control_status(dep);
> +	if (ret)
> +		dev_warn(dwc->dev,
> +			"ep0 status phase start transfer failed: %d\n", ret);
>  }
>  
>  static void dwc3_ep0_do_control_status(struct dwc3 *dwc,
> @@ -1121,7 +1130,10 @@ void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep)
>  	cmd |= DWC3_DEPCMD_PARAM(dep->resource_index);
>  	memset(&params, 0, sizeof(params));
>  	ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
> -	WARN_ON_ONCE(ret);
> +	if (ret)
> +		dev_warn_ratelimited(dwc->dev,
> +			"ep0 data phase end transfer failed: %d\n", ret);
> +
>  	dep->resource_index = 0;
>  }
>  
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 321361288935..50e4f667b2f2 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1774,7 +1774,11 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
>  		dep->flags |= DWC3_EP_DELAY_STOP;
>  		return 0;
>  	}
> -	WARN_ON_ONCE(ret);
> +
> +	if (ret)
> +		dev_warn_ratelimited(dep->dwc->dev,
> +				"end transfer failed: ret = %d\n", ret);
> +
>  	dep->resource_index = 0;
>  
>  	if (!interrupt)
> @@ -4041,7 +4045,9 @@ static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)
>  		dep->flags &= ~DWC3_EP_STALL;
>  
>  		ret = dwc3_send_clear_stall_ep_cmd(dep);
> -		WARN_ON_ONCE(ret);
> +		if (ret)
> +			dev_warn_ratelimited(dwc->dev,
> +				"failed to clear STALL on %s\n", dep->name);
>  	}
>  }
>  
> -- 
> 2.17.1
>