Dne 11. 06. 20 v 11:44 Vinod Koul napsal(a):
On 11-06-20, 11:09, Jaroslav Kysela wrote:
Dne 11. 06. 20 v 10:46 Charles Keepax napsal(a):
On Wed, Jun 10, 2020 at 04:28:20PM +0530, Vinod Koul wrote:
On 10-06-20, 12:40, Jaroslav Kysela wrote:
Dne 10. 06. 20 v 12:07 Srinivas Kandagatla napsal(a):
For gapless playback call to snd_compr_drain_notify() after
partial drain should put the state to SNDRV_PCM_STATE_RUNNING
rather than SNDRV_PCM_STATE_SETUP as the driver is ready to
process the buffers for new track.
With existing code, if we are playing 3 tracks in gapless, after
partial drain finished on previous track 1 the state is set to
SNDRV_PCM_STATE_SETUP which is then moved to SNDRV_PCM_STATE_PREPARED
after data write. With this state calls to snd_compr_next_track() and
few other calls will fail as they expect the state to be in
SNDRV_PCM_STATE_RUNNING.
Here is the sequence of events and state transitions:
1. set_params (Track 1), state = SNDRV_PCM_STATE_SETUP
2. set_metadata (Track 1), no state change, state = SNDRV_PCM_STATE_SETUP
3. fill and trigger start (Track 1), state = SNDRV_PCM_STATE_RUNNING
4. set_next_track (Track 2), state = SNDRV_PCM_STATE_RUNNING
5. partial_drain (Track 1), state = SNDRV_PCM_STATE_SETUP
6 snd_compr_drain_notify (Track 1), state = SNDRV_PCM_STATE_SETUP
7. fill data (Track 2), state = SNDRV_PCM_STATE_PREPARED
8. set_metadata (Track 3), no state change, state = SNDRV_PCM_STATE_PREPARED
9. set_next_track (Track 3), !! FAILURE as state != SNDRV_PCM_STATE_RUNNING
The snd_compr_drain_notify() is called only from snd_compr_stop(). Something
is missing in this sequence?
It is supposed to be invoked by driver when partial drain is complete..
both intel and sprd driver are calling this. snd_compr_stop is stop
while draining case so legit
Not sure I follow this statement, could you elaborate a bit?
snd_compr_stop putting the state to RUNNING seems fundamentally
broken to me, the whole point of snd_compr_stop is to take the
state out of RUNNING.
Yes. I agree. It seems that the acknowledge for the partial drain should be
handled differently.
Yeah sorry I overlooked that case and was thinking of it being invoked
from driver!
Yes this would make the snd_compr_stop() behave incorrectly.. so this
cant be done as proposed.
But we still need to set the draining stream state properly and I am
thinking below now:
diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 509290f2efa8..9aba851732d7 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -929,7 +929,9 @@ static int snd_compr_partial_drain(struct snd_compr_stream *stream)
}
stream->next_track = false;
- return snd_compress_wait_for_drain(stream);
+ retval = snd_compress_wait_for_drain(stream);
+ stream->runtime->state = SNDRV_PCM_STATE_RUNNING;
+ return retval;
}
I see a race possibility when the last track is too small and the driver
signals the end-of-track twice. In this case the partial drain should not end
with the running state. It would be probably better to separate partial / last
track acknowledgements.
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
