[alsa-devel] [PATCH] ALSA: usb-audio: Fix parsing descriptor of UAC2 processing unit

[Ruslan Bilovol]

On Mon, Mar 19, 2018 at 5:45 PM, Takashi Iwai <tiwai at suse.de> wrote:
> On Mon, 19 Mar 2018 08:47:49 +0100,
> Takashi Iwai wrote:
>>
>> On Mon, 19 Mar 2018 08:40:19 +0100,
>> Greg Kroah-Hartman wrote:
>> >
>> > On Mon, Mar 19, 2018 at 07:11:08AM +0100, Kirill Marinushkin wrote:
>> > > Currently, the offsets in the UAC2 processing unit descriptor are
>> > > calculated incorrectly. It causes an issue when connecting the device which
>> > > provides such a feature:
>> > >
>> > > ~~~~
>> > > [84126.724420] usb 1-1.3.1: invalid Processing Unit descriptor (id 18)
>> > > ~~~~
>> > >
>> > > After this patch is applied, the UAC2 processing unit inits w/o this error.
>> > >
>> > > Fixes: 5e1ddb481776 ("UAPI: (Scripted) Disintegrate include/linux/usb")
>> > > Signed-off-by: Kirill Marinushkin <k.marinushkin at gmail.com>
>> > > Cc: Mark Brown <broonie at kernel.org>
>> > > Cc: Jaroslav Kysela <perex at perex.cz>
>> > > Cc: Takashi Iwai <tiwai at suse.com>
>> > > Cc: Thomas Gleixner <tglx at linutronix.de>
>> > > Cc: Felipe Balbi <felipe.balbi at linux.intel.com>
>> > > Cc: Philippe Ombredanne <pombredanne at nexb.com>
>> > > Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
>> > > Cc: Ruslan Bilovol <ruslan.bilovol at gmail.com>
>> > > Cc: linux-kernel at vger.kernel.org
>> > > Cc: alsa-devel at alsa-project.org
>> > > ---
>> > >  include/uapi/linux/usb/audio.h | 4 ++--
>> > >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> >     Cc: stable <stable at vger.kernel.org>
>> >  perhaps?
>>
>> Yes, it deserves.  But I'd need to double-check the UAC2
>> specification.  It's interesting that such a basic thing hasn't hit
>> until now.  Maybe just because it's a fairly minor feature.
>
> ... and the patch looks correct, after confirming the UAC2 spec.
> Now I applied it, with a minor correction of Fixes tag, which actually
> was introduced by 23caaf19b11e ("ALSA: usb-mixer: Add support for
> Audio Class v2.0"), and adding Cc to stable.
>

I also checked UAC1/UAC2 spec and the patch looks good.
What's interesting it seems nobody faced this issue (after searching
ower Internet can't find any mention) which was present from the
beginning of UAC2 driver implementation.

Thanks,
Ruslan