[alsa-devel] [PATCH] ALSA: hda: Disable 4/6 channels on some NVIDIA GPUs.

[Takashi Iwai]

At Tue, 11 Jan 2011 19:11:53 +0200,
Anssi Hannula wrote:
> 
> On 10.01.2011 18:19, Nitin Daga wrote:
> > Added hardware constraint in patch_hdmi.c to disable
> > channels 4/6 which are not supported by some older
> > NVIDIA GPUs.
> 
> And 3/5/7, which do not seem to work either with my 0x0007.
> 
> However, 3/5/7 do not work with my 0x000b system either, is this a hw
> limitation as well (that should be added to the driver) or is there a
> bug in the HDA driver for uneven channel counts?

In theory yes, but I don't know any really working codecs.  It seems
that codecs (or controllers?) are designed to take always
stereo-pairs.

Maybe we can put a hw_constraint in hda_intel.c.


thanks,

Takashi

> (I looked at the HDA specification and it does seem to allow
> odd-numbered channel counts)
> 
> Strangely, on both of my systems speaker-test -c5 fails with an error:
> 
> $ speaker-test -Dhdmi -c5
> 
> speaker-test 1.0.23
> 
> Playback device is hdmi
> Stream parameters are 48000Hz, S16_LE, 5 channels
> Using 16 octaves of pink noise
> Rate set to 48000Hz (requested 48000Hz)
> Buffer size range from 128 to 419392
> Period size range from 64 to 209664
> Using max buffer size 419392
> Periods = 4
> Unable to set nperiods 4 for playback: No such file or directory
> Setting of hwparams failed: No such file or directory
> 
> While -c3 and -c7 run fine but no sound is received.
> 
> 
> > Signed-off-by: Nitin Daga <ndaga at nvidia.com>
> > Acked-By: Stephen Warren <swarren at nvidia.com>
> > ---
> >  pci/hda/patch_hdmi.c |   42 ++++++++++++++++++++++++++++++++++++++++++
> >  1 files changed, 42 insertions(+), 0 deletions(-)
> > 
> > diff --git a/pci/hda/patch_hdmi.c b/pci/hda/patch_hdmi.c
> > index d3e49aa..ddde59b 100644
> > --- a/pci/hda/patch_hdmi.c
> > +++ b/pci/hda/patch_hdmi.c
> > @@ -1166,11 +1166,53 @@ static int nvhdmi_7x_init(struct hda_codec *codec)
> >  	return 0;
> >  }
> >  
> > +static unsigned int channels_2_6_8[] = {
> > +	2, 6, 8
> > +};
> > +
> > +static unsigned int channels_2_8[] = {
> > +	2, 8
> > +};
> > +
> > +static struct snd_pcm_hw_constraint_list hw_constraints_2_6_8_channels = {
> > +	.count = ARRAY_SIZE(channels_2_6_8),
> > +	.list = channels_2_6_8,
> > +	.mask = 0,
> > +};
> > +
> > +static struct snd_pcm_hw_constraint_list hw_constraints_2_8_channels = {
> > +	.count = ARRAY_SIZE(channels_2_8),
> > +	.list = channels_2_8,
> > +	.mask = 0,
> > +};
> > +
> >  static int simple_playback_pcm_open(struct hda_pcm_stream *hinfo,
> >  				    struct hda_codec *codec,
> >  				    struct snd_pcm_substream *substream)
> >  {
> >  	struct hdmi_spec *spec = codec->spec;
> > +	struct snd_pcm_hw_constraint_list *hw_constraints_channels = NULL;
> > +
> > +	switch (codec->preset->id) {
> > +	case 0x10de0002:
> > +	case 0x10de0003:
> > +	case 0x10de0005:
> > +	case 0x10de0006:
> > +		hw_constraints_channels = &hw_constraints_2_8_channels;
> > +		break;
> > +	case 0x10de0007:
> > +		hw_constraints_channels = &hw_constraints_2_6_8_channels;
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +
> > +	if (hw_constraints_channels != NULL) {
> > +		snd_pcm_hw_constraint_list(substream->runtime, 0,
> > +				SNDRV_PCM_HW_PARAM_CHANNELS,
> > +				hw_constraints_channels);
> > +	}
> > +
> >  	return snd_hda_multi_out_dig_open(codec, &spec->multiout);
> >  }
> >  
> 
> 
> -- 
> Anssi Hannula
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