[alsa-devel] [PATCH 1/4] ALSA: x86: Don't pass SNDRV_PCM_INFO_BATCH flag

[Pierre-Louis Bossart]

On 2/3/17 10:43 AM, Takashi Iwai wrote:
> The PCM engine on LPE audio isn't like a batch-style process, but
> rather it deals with the standard ring buffer.  Passing the BATCH info
> flag is inappropriate.

Humm, this is controversial. There are 4 DMA descriptors and getting a 
precise position in the stream is not straightforward. Rewind is also 
not supported so if you remove the BATCH flag you will push PulseAudio 
into doing timer-based scheduling and rewinds that probably don't work.

>
> Similarly, the DOUBLE flag is also superfluous.  Drop both bits.
>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> ---
>  sound/x86/intel_hdmi_audio.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/sound/x86/intel_hdmi_audio.c b/sound/x86/intel_hdmi_audio.c
> index c83f02c2593e..32a21422e6f5 100644
> --- a/sound/x86/intel_hdmi_audio.c
> +++ b/sound/x86/intel_hdmi_audio.c
> @@ -131,10 +131,8 @@ static const struct channel_map_table map_tables[] = {
>  /* hardware capability structure */
>  static const struct snd_pcm_hardware snd_intel_hadstream = {
>  	.info =	(SNDRV_PCM_INFO_INTERLEAVED |
> -		SNDRV_PCM_INFO_DOUBLE |
>  		SNDRV_PCM_INFO_MMAP|
> -		SNDRV_PCM_INFO_MMAP_VALID |
> -		SNDRV_PCM_INFO_BATCH),
> +		SNDRV_PCM_INFO_MMAP_VALID),
>  	.formats = (SNDRV_PCM_FMTBIT_S24 |
>  		SNDRV_PCM_FMTBIT_U24),
>  	.rates = SNDRV_PCM_RATE_32000 |
>