Re: [PATCH] ALSA: hda - Always allow basic audio irrespective of ELD info

[Takashi Iwai <tiwai@suse.de>]

At Tue,  7 Dec 2010 20:56:19 +0200,
Anssi Hannula wrote:
> 
> Commit bbbe33900d1f3c added functionality to restrict PCM parameters
> based on ELD info (derived from EDID data) of the audio sink.
> 
> However, according to CEA-861-D no SAD is needed for basic audio
> (32/44.1/48kHz stereo 16-bit audio), which is instead indicated with a
> basic audio flag in the CEA EDID Extension.
> 
> The flag is not present in ELD. However, as all audio capable sinks are
> required to support basic audio, we can assume it to be always
> available.
> 
> Fix allowed audio formats with sinks that have SADs (Short Audio
> Descriptors) which do not completely overlap with the basic audio
> formats (there are no reports of affected devices so far) by always
> assuming that basic audio is supported.
> 
> Reported-by: Stephen Warren <swarren@nvidia.com>
> Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
> ---
> 
> Tested on 2.6.36 and I saw no obvious regressions.
> 
> The issue affects stable 2.6.36 as well, but as there are no reports of
> affected devices, I'll leave the decision on whether to send this to
> stable@ for the ALSA subsystem maintainers.

I'm inclined for adding stable in this case, because this is more
"safer" move for users.

Will the patch "ALSA: hda - Do not wrongly restrict min_channels based
on ELD" be resent or shall I apply it as is now together with this?


thanks,

Takashi


> 
>  sound/pci/hda/hda_eld.c |   16 +++++++---------
>  1 files changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_eld.c b/sound/pci/hda/hda_eld.c
> index 47ef8aa..009031f 100644
> --- a/sound/pci/hda/hda_eld.c
> +++ b/sound/pci/hda/hda_eld.c
> @@ -598,21 +598,19 @@ void hdmi_eld_update_pcm_info(struct hdmi_eld *eld, struct hda_pcm_stream *pcm,
>  {
>  	int i;
>  
> -	pcm->rates = 0;
> -	pcm->formats = 0;
> -	pcm->maxbps = 0;
> -	pcm->channels_max = 0;
> +	/* assume basic audio support (the basic audio flag is not in ELD;
> +	 * however, all audio capable sinks are required to support basic
> +	 * audio) */
> +	pcm->rates = SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000;
> +	pcm->formats = SNDRV_PCM_FMTBIT_S16_LE;
> +	pcm->maxbps = 16;
> +	pcm->channels_max = 2;
>  	for (i = 0; i < eld->sad_count; i++) {
>  		struct cea_sad *a = &eld->sad[i];
>  		pcm->rates |= a->rates;
>  		if (a->channels > pcm->channels_max)
>  			pcm->channels_max = a->channels;
>  		if (a->format == AUDIO_CODING_TYPE_LPCM) {
> -			if (a->sample_bits & AC_SUPPCM_BITS_16) {
> -				pcm->formats |= SNDRV_PCM_FMTBIT_S16_LE;
> -				if (pcm->maxbps < 16)
> -					pcm->maxbps = 16;
> -			}
>  			if (a->sample_bits & AC_SUPPCM_BITS_20) {
>  				pcm->formats |= SNDRV_PCM_FMTBIT_S32_LE;
>  				if (pcm->maxbps < 20)
> -- 
> 1.7.3
>