[alsa-devel] [PATCH 1/2] snd-usb-audio: Skip un-parseable mixer units instead of erroring

[Mark Hills]

On Sat, 14 Apr 2012, Takashi Iwai wrote:

> At Sat, 14 Apr 2012 17:19:23 +0100,
> Mark Hills wrote:
> > 
> > Some interfaces reference endpoints which do not exists. To
> > accomodate these, do not fail completely, but skip over them.
> > 
> > This allows the Electrix Ebox-44 with earlier firmware to be
> > detected and used for audio.
> 
> Does the driver warn something?  Ignoring silently doesn't sound
> right...

Yes, parse_audio_unit already reports the error. Though I didn't do an 
exhaustive check for all cases.

The suggestion to do this came from Clemens (see thread "usb-audio: 
Correct way to do a mixer quirk?"). Originally I was hoping to just quirk 
this for the specific device, but the rest of the driver does also seem to 
be fairly tolerant of errors if it means more devices can be used.

> 
> Takashi
> 
> > 
> > Signed-off-by: Mark Hills <mark at pogo.org.uk>
> > ---
> >  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 ab23869..c374c72 100644
> > --- a/sound/usb/mixer.c
> > +++ b/sound/usb/mixer.c
> > @@ -1388,7 +1388,7 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, void *r
> >  	for (pin = 0; pin < input_pins; pin++) {
> >  		err = parse_audio_unit(state, desc->baSourceID[pin]);
> >  		if (err < 0)
> > -			return err;
> > +			continue;
> >  		err = check_input_term(state, desc->baSourceID[pin], &iterm);
> >  		if (err < 0)
> >  			return err;
> > -- 
> > 1.7.4.4
> > 
> 

-- 
Mark