linux-kernel - Re: [PATCH] usb: dwc3: Abort suspend on soft disconnect failure

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Message-ID: <20250321220346.wwt3vfwmrcq3qwzj@synopsys.com>
Date: Fri, 21 Mar 2025 22:03:48 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Kuen-Han Tsai <khtsai@...gle.com>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc3: Abort suspend on soft disconnect failure

On Thu, Mar 20, 2025, Kuen-Han Tsai wrote:
> When dwc3_gadget_soft_disconnect() fails, dwc3_suspend_common() keeps
> going with the suspend, resulting in a period where the power domain is
> off, but the gadget driver remains connected.  Within this time frame,
> invoking vbus_event_work() will cause an error as it attempts to access
> DWC3 registers for endpoint disabling after the power domain has been
> completely shut down.
> 
> Abort the suspend sequence when dwc3_gadget_suspend() cannot halt the
> controller and proceeds with a soft connect.
> 
> CC: stable@...r.kernel.org

Please add Fixes tag.

> Signed-off-by: Kuen-Han Tsai <khtsai@...gle.com>
> ---
> 
> Kernel panic - not syncing: Asynchronous SError Interrupt
> Workqueue: events vbus_event_work
> Call trace:
>  dump_backtrace+0xf4/0x118
>  show_stack+0x18/0x24
>  dump_stack_lvl+0x60/0x7c
>  dump_stack+0x18/0x3c
>  panic+0x16c/0x390
>  nmi_panic+0xa4/0xa8
>  arm64_serror_panic+0x6c/0x94
>  do_serror+0xc4/0xd0
>  el1h_64_error_handler+0x34/0x48
>  el1h_64_error+0x68/0x6c
>  readl+0x4c/0x8c
>  __dwc3_gadget_ep_disable+0x48/0x230
>  dwc3_gadget_ep_disable+0x50/0xc0
>  usb_ep_disable+0x44/0xe4
>  ffs_func_eps_disable+0x64/0xc8
>  ffs_func_set_alt+0x74/0x368
>  ffs_func_disable+0x18/0x28
>  composite_disconnect+0x90/0xec
>  configfs_composite_disconnect+0x64/0x88
>  usb_gadget_disconnect_locked+0xc0/0x168
>  vbus_event_work+0x3c/0x58
>  process_one_work+0x1e4/0x43c
>  worker_thread+0x25c/0x430
>  kthread+0x104/0x1d4
>  ret_from_fork+0x10/0x20
> 
> ---
>  drivers/usb/dwc3/core.c   | 10 +++++++---
>  drivers/usb/dwc3/gadget.c | 22 +++++++++-------------
>  2 files changed, 16 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 66a08b527165..d64d17677bdb 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2387,7 +2387,7 @@ static int dwc3_core_init_for_resume(struct dwc3 *dwc)
>  static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  {
>  	u32 reg;
> -	int i;
> +	int i, ret;

Minor nit: Can we keep declarations in separate lines.

> 
>  	if (!pm_runtime_suspended(dwc->dev) && !PMSG_IS_AUTO(msg)) {
>  		dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
> @@ -2406,7 +2406,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  	case DWC3_GCTL_PRTCAP_DEVICE:
>  		if (pm_runtime_suspended(dwc->dev))
>  			break;
> -		dwc3_gadget_suspend(dwc);
> +		ret = dwc3_gadget_suspend(dwc);
> +		if (ret)
> +			return ret
>  		synchronize_irq(dwc->irq_gadget);
>  		dwc3_core_exit(dwc);
>  		break;
> @@ -2441,7 +2443,9 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  			break;
> 
>  		if (dwc->current_otg_role == DWC3_OTG_ROLE_DEVICE) {
> -			dwc3_gadget_suspend(dwc);
> +			ret = dwc3_gadget_suspend(dwc);
> +			if (ret)
> +				return ret;
>  			synchronize_irq(dwc->irq_gadget);
>  		}
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 89a4dc8ebf94..316c1589618e 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -4776,26 +4776,22 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
>  	int ret;
> 
>  	ret = dwc3_gadget_soft_disconnect(dwc);
> -	if (ret)
> -		goto err;
> -
> -	spin_lock_irqsave(&dwc->lock, flags);
> -	if (dwc->gadget_driver)
> -		dwc3_disconnect_gadget(dwc);
> -	spin_unlock_irqrestore(&dwc->lock, flags);
> -
> -	return 0;
> -
> -err:
>  	/*
>  	 * Attempt to reset the controller's state. Likely no
>  	 * communication can be established until the host
>  	 * performs a port reset.
>  	 */
> -	if (dwc->softconnect)
> +	if (ret && dwc->softconnect) {
>  		dwc3_gadget_soft_connect(dwc);
> +		return ret;
> +	}
> 
> -	return ret;
> +	spin_lock_irqsave(&dwc->lock, flags);
> +	if (dwc->gadget_driver)
> +		dwc3_disconnect_gadget(dwc);
> +	spin_unlock_irqrestore(&dwc->lock, flags);
> +
> +	return 0;
>  }
> 
>  int dwc3_gadget_resume(struct dwc3 *dwc)
> --
> 2.49.0.395.g12beb8f557-goog
> 

The rest looks good.

Thanks,
Thinh