Re: Logitech USB headset not working in 3.6-rc3

[Daniel Mack <zonque@gmail.com>]

On 29.08.2012 16:14, Takashi Iwai wrote:
> At Wed, 29 Aug 2012 15:32:34 +0200,
> Daniel Mack wrote:
>>
>> [1  <text/plain; ISO-8859-1 (7bit)>]
>> On 29.08.2012 15:29, Takashi Iwai wrote:
>>> At Wed, 29 Aug 2012 13:26:25 +0200,
>>> Daniel Mack wrote:
>>>>
>>>> [1  <text/plain; ISO-8859-1 (7bit)>]
>>>> On 25.08.2012 14:17, Josh Boyer wrote:
>>>>> On Sat, Aug 25, 2012 at 02:13:58PM +0200, Daniel Mack wrote:
>>>>>> On 25.08.2012 14:07, Bruno Wolff III wrote:
>>>>>>> On Sat, Aug 25, 2012 at 14:02:51 +0200,
>>>>>>>    Daniel Mack <zonque@gmail.com> wrote:
>>>>>>>>
>>>>>>>> Can you revert commit e9ba389c5 ("ALSA: usb-audio: Fix
>>>>>>>> scheduling-while-atomic bug in PCM capture stream") and see if that
>>>>>>>
>>>>>>> I can try that, but it takes a long time to build a new kernel on my 
>>>>>>> old hardware.
>>>>>>>
>>>>>>>> helps? If not, can you summarize again which kernels still work for you
>>>>>>>> and which don't?
>>>>>>>
>>>>>>> The latest kernel that works is 3.6.0-0.rc2.git1.2.fc18. The earliest that 
>>>>>>> doesn't work is 3.6.0-0.rc2.git2.1.fc18.
>>>>>>>
>>>>>>
>>>>>> The report you sent doesn't look like it could be caused by e9ba389c5.
>>>>>> It fixes a kernel Ooops. But as it is the only relevant patch in that
>>>>>> area, it would be interesting if reverting it fixes anything.
>>>>>
>>>>> Yep, agreed.  If this revert kernel doesn't work, we're likely down to a
>>>>> git bisect, Bruno.
>>>>>
>>>>>> Btw - thanks a lot for testing -rc kernels, much appreciated!
>>>>>
>>>>> Indeed!
>>>>
>>>> Could you please try this patch on top of Takashi's? Thanks again!
>>>>
>>>>
>>>> Daniel
>>>>
>>>> [2 0001-ALSA-snd-usb-Fix-URB-cancellation-at-stream-start.patch <text/x-patch (7bit)>]
>>>> >From 6617bb2463ae3fad21390b59cc2a71f96b9e9ca8 Mon Sep 17 00:00:00 2001
>>>> From: Daniel Mack <zonque@gmail.com>
>>>> Date: Wed, 29 Aug 2012 13:17:05 +0200
>>>> Subject: [PATCH] ALSA: snd-usb: Fix URB cancellation at stream start
>>>>
>>>> Commit e9ba389c5 ("ALSA: usb-audio: Fix scheduling-while-atomic bug in
>>>> PCM capture stream") fixed a scheduling-while-atomic bug that happened
>>>> when snd_usb_endpoint_start was called from the trigger callback, which
>>>> is an atmic context. However, the patch breaks the idea of the endpoints
>>>> reference counting, which is the reason why the driver has been
>>>> refactored lately.
>>>>
>>>> Revert that commit and let snd_usb_endpoint_start() take care of the URB
>>>> cancellation again. As this function is called from both atomic and
>>>> non-atomic context, add a flag to denote whether the function may sleep.
>>>>
>>>> Signed-off-by: Daniel Mack <zonque@gmail.com>
>>>> Cc: stable@kernel.org [3.5+]
>>>> ---
>>>>  sound/usb/endpoint.c | 10 ++++++++--
>>>>  sound/usb/endpoint.h |  2 +-
>>>>  sound/usb/pcm.c      | 13 +++++--------
>>>>  3 files changed, 14 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
>>>> index c411812..678456c 100644
>>>> --- a/sound/usb/endpoint.c
>>>> +++ b/sound/usb/endpoint.c
>>>> @@ -799,7 +799,9 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
>>>>  /**
>>>>   * snd_usb_endpoint_start: start an snd_usb_endpoint
>>>>   *
>>>> - * @ep: the endpoint to start
>>>> + * @ep:		the endpoint to start
>>>> + * @can_sleep:	flag indicating whether the operation is executed in
>>>> + * 		non-atomic context
>>>>   *
>>>>   * A call to this function will increment the use count of the endpoint.
>>>>   * In case it is not already running, the URBs for this endpoint will be
>>>> @@ -809,7 +811,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
>>>>   *
>>>>   * Returns an error if the URB submission failed, 0 in all other cases.
>>>>   */
>>>> -int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
>>>> +int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep)
>>>>  {
>>>>  	int err;
>>>>  	unsigned int i;
>>>> @@ -821,6 +823,10 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
>>>>  	if (++ep->use_count != 1)
>>>>  		return 0;
>>>>  
>>>> +	/* just to be sure */
>>>> +	deactivate_urbs(ep, 0, can_sleep);
>>>> +	wait_clear_urbs(ep);
>>>
>>> It'd be safer to protect the call of wait_clear_urbs() when
>>> can_sleep=0.
>>
>> Right. New patch attached.
> 
> Thanks.  This makes me thinking whether we really need to call
> deactivate_urbs() at snd_usb_endpoint_start().  deactivate_endpoints()
> is called already in prepare (at the beginning).  Which possibility is
> considered?  The comment "just to be sure" implies that my original
> code before your stream model change was simply optional.  Now I'm not
> quite sure whether we can drop it or not...

Yes, we can most probably drop it, but I would clearly do that in
another patch for 3.6 - I'll prepare one.

I also found some regressions caused by the recent refactoring, and will
send out a patch collection, hopefully later today.


Daniel