[alsa-devel] Why is ALSA sending STOP/START commands to my driver during MP3 playback?

[Timur Tabi]

I'm developing an ASoC driver, and when I play an MP3 with mpg123, my driver's 
trigger() function is called with the SNDRV_PCM_TRIGGER_STOP command and then 
is immediately called again with SNDRV_PCM_TRIGGER_START.

Can someone tell me why ALSA would do this?

This only happens when playing an MP3.  When I use aplay to play a regular 
Wave file, I don't see this behavior.

My driver does not have the SNDRV_PCM_INFO_PAUSE bit set, because I haven't 
gotten around to testing that capability.  I suspect that if I did have that 
bit set, I would be getting SNDRV_PCM_TRIGGER_PAUSE_PUSH and 
SNDRV_PCM_TRIGGER_PAUSE_RELEASE calls instead.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale