linux-kernel - Re: [PATCH v3] usb: dwc3: Abort suspend on soft disconnect failure

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Message-ID: <CAKzKK0oqdxvnfGg6GR_N3M59fdPqR+uTW=YC6SPGOB7+aojV_A@mail.gmail.com>
Date: Wed, 16 Apr 2025 18:39:39 +0800
From: Kuen-Han Tsai <khtsai@...gle.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
	stable@...r.kernel.org
Subject: Re: [PATCH v3] usb: dwc3: Abort suspend on soft disconnect failure

On Thu, Mar 27, 2025 at 9:32 PM Kuen-Han Tsai <khtsai@...gle.com> 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.
>
> Fixes: 9f8a67b65a49 ("usb: dwc3: gadget: fix gadget suspend/resume")
> CC: stable@...r.kernel.org
> 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
>
> ---
> Changelog:
>
> v3:
> - change the Fixes tag
>
> v2:
> - move declarations in separate lines
> - add the Fixes tag
>
> ---
>  drivers/usb/dwc3/core.c   |  9 +++++++--
>  drivers/usb/dwc3/gadget.c | 22 +++++++++-------------
>  2 files changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 66a08b527165..1cf1996ae1fb 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2388,6 +2388,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  {
>         u32 reg;
>         int i;
> +       int ret;
>
>         if (!pm_runtime_suspended(dwc->dev) && !PMSG_IS_AUTO(msg)) {
>                 dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
> @@ -2406,7 +2407,9 @@ 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

Sorry about forgetting the semicolon.

>                 synchronize_irq(dwc->irq_gadget);
>                 dwc3_core_exit(dwc);
>                 break;
> @@ -2441,7 +2444,9 @@ 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;

This should return -EAGAIN after a soft connect to keep dwc3 active,
allowing dwc3_gadget_pullup() to perform the subsequent pull-down
normally.

> +       }
>
> -       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)
> --
> 2.49.0.472.ge94155a9ec-goog
>

Hi Thinh and Greg,

Sorry again for the lack of thorough testing on my patches. I've
corrected silly mistakes and sent out v4.

https://lore.kernel.org/linux-usb/20250416100515.2131853-1-khtsai@google.com/

Thanks,
Kuen-Han