[alsa-devel] [PATCH] ALSA: usb-audio: fix PCM device order

[Takashi Iwai]

On Sat, 27 Jul 2019 10:09:08 +0200,
Tanu Kaskinen wrote:
> 
> Ping? This patch never got any feedback, and yesterday another user
> complained on PulseAudio bug tracker that Audinst HUD-mx2 doesn't work
> out of the box, because by default hw:x,0 is used when hw:x,1 is the
> pcm that works.

Oohoo, it's a ping with so large latency.  This must have been simply
overlooked, or I was off at that time.

In anyway the patch can't be applied to the latest code as of today,
so I rewrote with a cleanup patch.

The patchset will be submitted, so please give it a try.


thanks,

Takashi

> 
> -- Tanu
> 
> 
> On Fri, 2017-08-11 at 02:36 +0300, Alexander Tsoy wrote:
> > Some cards have alternate setting with non-PCM format as the first
> > altsetting in the interface descriptors. This confuses userspace, since
> > alsa-lib uses device 0 by default. So lets parse interfaces in two steps:
> >  1. Parse altsettings with PCM formats.
> >  2. Parse altsettings with non-PCM formats.
> > 
> > This fixes at least following cards:
> >  - Audinst HUD-mx2
> >  - Audinst HUD-mini
> > 
> > Signed-off-by: Alexander Tsoy <alexander at tsoy.me>
> > ---
> >  sound/usb/stream.c | 27 ++++++++++++++++++++++++++-
> >  1 file changed, 26 insertions(+), 1 deletion(-)
> > 
> > diff --git a/sound/usb/stream.c b/sound/usb/stream.c
> > index 8e9548bc1f1a..b2ebeae91396 100644
> > --- a/sound/usb/stream.c
> > +++ b/sound/usb/stream.c
> > @@ -477,7 +477,8 @@ static struct uac2_output_terminal_descriptor *
> >  	return NULL;
> >  }
> >  
> > -int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
> > +static int __snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no,
> > +				           bool *has_non_pcm, bool non_pcm)
> >  {
> >  	struct usb_device *dev;
> >  	struct usb_interface *iface;
> > @@ -634,6 +635,10 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
> >  				iface_no, altno);
> >  			continue;
> >  		}
> > +		if (fmt->bFormatType != UAC_FORMAT_TYPE_I)
> > +			*has_non_pcm = true;
> > +		if ((fmt->bFormatType == UAC_FORMAT_TYPE_I) == non_pcm)
> > +			continue;
> >  		if (((protocol == UAC_VERSION_1) && (fmt->bLength < 8)) ||
> >  		    ((protocol == UAC_VERSION_2) && (fmt->bLength < 6))) {
> >  			dev_err(&dev->dev,
> > @@ -740,3 +745,23 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
> >  	return 0;
> >  }
> >  
> > +int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
> > +{
> > +	int err;
> > +	bool has_non_pcm = false;
> > +
> > +	/* parse PCM formats */
> > +	err = __snd_usb_parse_audio_interface(chip, iface_no, &has_non_pcm, false);
> > +	if (err < 0)
> > +		return err;
> > +
> > +	if (has_non_pcm) {
> > +		/* parse non-PCM formats */
> > +		err = __snd_usb_parse_audio_interface(chip, iface_no, &has_non_pcm, true);
> > +		if (err < 0)
> > +			return err;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> 
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