linux-kernel - Re: USB deadlock after resume

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Date:	Wed, 21 Nov 2007 08:52:21 -0600
From:	Felipe Balbi <me@...ipebalbi.com>
To:	Markus Rechberger <mrechberger@...il.com>
Cc:	Oliver Neukum <oliver@...kum.org>, 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

Hi,

On Wed, 21 Nov 2007 15:37:20 +0100, "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.

This device shouldn't be suspended. AFAIK it should have auto_suspend
disabled
by default.

Try adding this device to drivers/usb/core/quirks.c with
USB_QUIRK_NO_AUTOSUSPEND flag set. Something like:

diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index d42c561..729eb4b 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -45,6 +45,9 @@ static const struct usb_device_id usb_quirk_list[] = {
        /* SKYMEDI USB_DRIVE */
        { USB_DEVICE(0x1516, 0x8628), .driver_info = USB_QUIRK_RESET_RESUME
},
 
+       /* Your device */
+       { USB_DEVICE(0x0000, 0x0000), .driver_info =
USB_QUIRK_NO_AUTOSUSPEND },
+
        { }  /* terminating entry must be last */
 };



> 
> Reloading the driver doesn't help at tht point, only reconnecting the
> device does.
> 
> The data is transfered using bulk transfer.
> 
> Markus
> -
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-- 
Best Regards,

Felipe Balbi
http://felipebalbi.com
me@...ipebalbi.com

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