[alsa-devel] [PATCH 3/6] ALSA: x86: Support S16 format

[Takashi Iwai]

On Tue, 07 Feb 2017 17:48:59 +0100,
Pierre-Louis Bossart wrote:
> 
> 
> 
> On 02/07/2017 07:11 AM, Takashi Iwai wrote:
> > Now we support S16 PCM format in addition.  For this, we need to set
> > packet_mode=1 in AUD_CONFIG register.
> While I think of it, there is a hidden benefit here. If this mode
> works, then most likely we can push IEC61937 data formatted as S16 PCM
> directly. For passthrough we needed to left-shit the data, if this
> mode does what it says it should make some people happy. The U,C,V
> should not be added in the data stream however (as done by the hdmi:
> plugin), there is a separate register to program then.

Yes, embedding the raw IEC data stream is an interesting move,
indeed.  But right now I'm not sure which configuration allows that
operation mode.

In my patch, I just played with AUD_CONFIG packet_mode bit.  Maybe
other fields (fmt, flat, user_bit) may play some relevant role?

Also, Channel Status 0 register have lots of uninitialized fields.
Some of ch0 bits are carried from AES status bits, but many are left
untouched.


thanks,

Takashi

> 
> >
> > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > ---
> >   sound/x86/intel_hdmi_audio.c | 8 +++++---
> >   1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/sound/x86/intel_hdmi_audio.c b/sound/x86/intel_hdmi_audio.c
> > index a0401476cd93..5697552f489a 100644
> > --- a/sound/x86/intel_hdmi_audio.c
> > +++ b/sound/x86/intel_hdmi_audio.c
> > @@ -136,7 +136,8 @@ static const struct snd_pcm_hardware had_pcm_hardware = {
> >   		SNDRV_PCM_INFO_MMAP|
> >   		SNDRV_PCM_INFO_MMAP_VALID |
> >   		SNDRV_PCM_INFO_BATCH),
> > -	.formats = (SNDRV_PCM_FMTBIT_S24_LE |
> > +	.formats = (SNDRV_PCM_FMTBIT_S16_LE |
> > +		    SNDRV_PCM_FMTBIT_S24_LE |
> >   		    SNDRV_PCM_FMTBIT_S32_LE),
> >   	.rates = SNDRV_PCM_RATE_32000 |
> >   		SNDRV_PCM_RATE_44100 |
> > @@ -308,12 +309,10 @@ static int had_prog_status_reg(struct snd_pcm_substream *substream,
> >   			   AUD_CH_STATUS_0, ch_stat0.regval);
> >     	switch (substream->runtime->format) {
> > -#if 0 /* FIXME: not supported yet */
> >   	case SNDRV_PCM_FORMAT_S16_LE:
> >   		ch_stat1.regx.max_wrd_len = MAX_SMPL_WIDTH_20;
> >   		ch_stat1.regx.wrd_len = SMPL_WIDTH_16BITS;
> >   		break;
> > -#endif
> >   	case SNDRV_PCM_FORMAT_S24_LE:
> >   	case SNDRV_PCM_FORMAT_S32_LE:
> >   		ch_stat1.regx.max_wrd_len = MAX_SMPL_WIDTH_24;
> > @@ -354,6 +353,9 @@ static int had_init_audio_ctrl(struct snd_pcm_substream *substream,
> >   	else
> >   		cfg_val.regx.layout = LAYOUT1;
> >   +	if (substream->runtime->format == SNDRV_PCM_FORMAT_S16_LE)
> > +		cfg_val.regx.packet_mode = 1;
> > +
> >   	if (substream->runtime->format == SNDRV_PCM_FORMAT_S32_LE)
> >   		cfg_val.regx.left_align = 1;
> >   
>