[alsa-devel] [PATCH 3/4] ALSA: usb-audio: parse UAC2 endpoint descriptors correctly

[Takashi Iwai]

At Thu, 27 May 2010 20:15:14 +0200,
Daniel Mack wrote:
> 
> On Thu, May 27, 2010 at 10:10:12AM +0200, Takashi Iwai wrote:
> > At Wed, 26 May 2010 13:46:57 -0700,
> > Greg KH wrote:
> > > 
> > > On Wed, May 26, 2010 at 06:17:46PM +0200, Daniel Mack wrote:
> > > > On Wed, May 26, 2010 at 06:11:38PM +0200, Daniel Mack wrote:
> > > > > UAC2 devices have their information about pitch control stored in a
> > > > > different field. Parse it, and emulate the bits for a v1 device.
> > > > > 
> > > > > A new struct uac2_iso_endpoint_descriptor is added.
> > > > 
> > > > > 
> > > > > Signed-off-by: Daniel Mack <daniel at caiaq.de>
> > > > > ---
> > > > >  include/linux/usb/audio-v2.h |   16 ++++++++++++
> > > > 
> > > > Greg, I copied you because of this patch, just to let you know we're
> > > > having fun in your area of responsibility again :)
> > > 
> > > Heh, no problem at all.
> > > 
> > > Takashi, feel free to add an:
> > > 	Acked-by: Greg Kroah-Hartman <gregkh at suse.de>
> > > to this patch when you take it.
> > 
> > OK, I put this to my tree.  Will be included in the next pull request
> > in this week.
> 
> Thanks Takashi!
> 
> Here's another small one that needs attention.
> 
> Daniel
> 
> >From 3beee40982b98314f8d58c775cc8b40a8e25ce18 Mon Sep 17 00:00:00 2001
> From: Daniel Mack <daniel at caiaq.de>
> Date: Thu, 27 May 2010 18:28:25 +0200
> Subject: [PATCH] ALSA: usb-audio: fix feature unit parser for UAC2
> 
> Fix a small off-by-one bug which causes the feature unit to announce a
> wrong number of channels. This leads to illegal requests sent to the
> firmware eventually.
> 
> Signed-off-by: Daniel Mack <daniel at caiaq.de>

OK, applied now.  Thanks.


Takashi

> ---
>  sound/usb/mixer.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 97dd176..03ce971 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -1126,7 +1126,7 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
>  	} else {
>  		struct uac2_feature_unit_descriptor *ftr = _ftr;
>  		csize = 4;
> -		channels = (hdr->bLength - 6) / 4;
> +		channels = (hdr->bLength - 6) / 4 - 1;
>  		bmaControls = ftr->bmaControls;
>  	}
>  
> -- 
> 1.7.1
>