Srini found issue with gapless implementation which prompted to look deeper into SM for compressed stream.
So documenting SM was first step, so first two patches add that. Last patch fixes the issue by keeping track on partial_drain and then moving state to 'running' in snd_compr_drain_notify() for partial_drain case on success. While at it, noticed snd_compr_drain_notify() is lockless state change, so fixed that as well.
I have tested this on Dragon board RB3, compressed audio works out of the box on that platform and Srini will send driver and fcplay patches for gapless soon.
Changes in v4: - Add review tag by Charles - fix the lock deadlock pointed by Charles
Changes in v3: - Add pause->stop->free transition - Add setup->free transition - remove running->free as that goes thru stop
Changes in v2: - Added tested tag by Srini - Update compress SM with Free state and compr_stop() transitions
Vinod Koul (3): ALSA: compress: document the compress audio state machine ALSA: compress: document the compress gapless audio state machine ALSA: compress: fix partial_drain completion state
.../sound/designs/compress-offload.rst | 83 +++++++++++++++++++ include/sound/compress_driver.h | 10 ++- sound/core/compress_offload.c | 4 + 3 files changed, 96 insertions(+), 1 deletion(-)