linux-kernel - Re: USB deadlock after resume

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Message-ID: <d9def9db0711210652v3cc6fbd7ta4650e0b8f61f422@mail.gmail.com>
Date:	Wed, 21 Nov 2007 15:52:37 +0100
From:	"Markus Rechberger" <mrechberger@...il.com>
To:	"Oliver Neukum" <oliver@...kum.org>
Cc:	"Mark Lord" <lkml@....ca>, linux-kernel@...r.kernel.org,
	linux-usb-devel@...ts.sourceforge.net,
	"Laurent Pinchart" <laurentp@...-semaphore.com>
Subject: Re: USB deadlock after resume

On 11/21/07, Markus Rechberger <mrechberger@...il.com> wrote:
> On 11/21/07, Markus Rechberger <mrechberger@...il.com> wrote:
> > On 11/21/07, Oliver Neukum <oliver@...kum.org> wrote:
> > > Am Mittwoch 21 November 2007 schrieb Markus Rechberger:
> > > > On 11/21/07, Markus Rechberger <mrechberger@...il.com> wrote:
> > > > > On 11/21/07, Mark Lord <lkml@....ca> wrote:
> > > > > > Markus Rechberger wrote:
> > > > > > > Hi,
> > > > > > >
> > > > > > > I'm looking at the linux uvc driver, and noticed after resuming
> my
> > > > > > ..
> > > > > >
> > > > > > Pardon me.. what is the "uvc" driver?  Which module/source file is
> > > that?
> > > > > >
> > > > >
> > > > > http://linux-uvc.berlios.de/ it's not yet included in the kernel
> > > > > sources although many distributions already ship it.
> > > > > A "dry" run putting the device into sleep mode works fine (I added a
> > > > > proc interface for calling those suspend/resume function).
> > > > >
> > > >
> > > > it's not just usb_set_interface that hangs actually.
> > > > It seems to hang at
> > > >
> > > > wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
> > > >
> > > > in drivers/usb/core/urb.c after resuming. I disabled access to the usb
> > > > subsystem in the uvc driver, although connecting any other usb storage
> > > > fails too, just at the same point.
> > >
> > > Which URB is usb_kill_urb() called for?
> > >
> >
> > it's the usb_control_message which calls usb_kill_urb if I haven't got
> > it wrong. (if you're looking for some other information please let me
> > know)
> > Although, I got a bit further with it. The error seems to happen
> > earlier already.
> > If I load the driver, and do not access the device after suspending
> > all usb_control commands fail with -71 eproto.
> >
> > Reloading the driver doesn't help at tht point, only reconnecting the
> > device does.
> >
> > The data is transfered using bulk transfer.
> >
>
> Do you know any good way for performing a softreset within the driver?
> The video application should get a continuous datastream after
> resuming the notebook, so the driver shouldn't be unloaded.
> The driver also keeps a list of previous camera settings which should
> be set up again after resuming. Stopping the video application and
> reattaching the device using ACPI (this board supports reconnecting
> the device using ACPI) should be avoided.
>

ok usb_reset_device() did the job after resuming. First problem solved.

Markus
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