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

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Message-ID: <CAKzKK0o__XbUhbFAn-uh-r-dLDCVOUr4JDYGDYnM2K0v_FrWPw@mail.gmail.com>
Date: Mon, 24 Mar 2025 11:25:06 +0800
From: Kuen-Han Tsai <khtsai@...gle.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc: "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 Sat, Mar 22, 2025 at 6:03 AM Thinh Nguyen <Thinh.Nguyen@...opsys.com> wrote:
>
> 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.

Sent out v2 version of the patch.
https://lore.kernel.org/linux-usb/20250324031758.865242-1-khtsai@google.com/

>
> > 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.

Fixed.

>
> >
> >       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

Thanks,
Kuen-Han