[PATCH] ASoC: qcom: q6asm-dai: Add SNDRV_PCM_INFO_BATCH flag

[Srinivas Kandagatla]

Thanks Stephan for finding this flag!

On 30/03/2020 18:52, Stephan Gerhold wrote:
> At the moment, playing audio with PulseAudio with the qdsp6 driver
> results in distorted sound. It seems like its timer-based scheduling
> does not work properly with qdsp6 since setting tsched=0 in
> the PulseAudio configuration avoids the issue.
> 
> Apparently this happens when the pointer() callback is not accurate
> enough. There is a SNDRV_PCM_INFO_BATCH flag that can be used to stop
> PulseAudio from using timer-based scheduling by default.
> 
> According to https://www.alsa-project.org/pipermail/alsa-devel/2014-March/073816.html:
> 
>      The flag is being used in the sense explained in the previous audio
>      meeting -- the data transfer granularity isn't fine enough but aligned
>      to the period size (or less).
> 
> q6asm-dai reports the position as multiple of
> 
>      prtd->pcm_count = snd_pcm_lib_period_bytes(substream)
> 
> so it indeed just a multiple of the period size.
> 
> Therefore adding the flag here seems appropriate and makes audio
> work out of the box.
> 
> Fixes: 2a9e92d371db ("ASoC: qdsp6: q6asm: Add q6asm dai driver")
> Cc: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
> Signed-off-by: Stephan Gerhold <stephan at gerhold.net>

Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>