[PATCH] ALSA: compress: allow pause and resume during draining
Gyeongtaek Lee
gt82.lee at samsung.com
Tue Sep 29 11:17:24 CEST 2020
On 9/29/20 06:14 PM, Takashi Iwai wrote:
>On Tue, 29 Sep 2020 10:40:51 +0200,
>Gyeongtaek Lee wrote:
>>
>> On 9/29/20 04:13 PM, Takashi Iwai wrote:
>> >On Tue, 29 Sep 2020 03:51:35 +0200,
>> >Gyeongtaek Lee wrote:
>> >>
>> >> On 9/28/20 11:35 PM, Pierre-Louis Bossart wrote:
>> >> >On 9/28/20 6:13 AM, Jaroslav Kysela wrote:
>> >> >> Dne 28. 09. 20 v 12:50 Gyeongtaek Lee napsal(a):
>> >> >>> With a stream with low bitrate, user can't pause or resume the stream
>> >> >>> near the end of the stream because current ALSA doesn't allow it.
>> >> >>> If the stream has very low bitrate enough to store whole stream into
>> >> >>> the buffer, user can't do anything except stop the stream and then
>> >> >>> restart it from the first.
>> >> >>> If pause and resume is allowed during draining, user experience can be
>> >> >>> enhanced.
>> >> >>
>> >> >> It seems that we need a new state to handle the pause + drain condition for
>> >> >> this case.
>> >> >>
>> >> >> With this proposed change, the pause state in drain is invisible.
>> >> >
>> >> >Indeed it's be much nicer to have a new state, e..g
>> >> >SNDRV_PCM_STATE_DRAINING_PAUSED.
>> >> Ok. I will add the new state.
>> >> >
>> >> >One concern is that states are defined in uapi/sound/asoc.h, so wouldn't
>> >> >this have impacts on userspace as well? We'd change the value of
>> >> >SNDRV_PCM_STATE_LAST.
>> >> >
>> >> I also agree that adding new state and increase LAST value in the header of uapi
>> >> could be dangerous. So, I added it to comress_offload.h for now.
>> >> It could be merged into snd_pcm_state_t in someday with big changes.
>> >> Could you review the fixed patch below?
>> >
>> >Hrm, this resulted in rather more complex changes than the original
>> >patch. It shows that introducing yet another state is no good idea
>> >for this particular case.
>> >
>> >Since the possible application's behavior after this pause is as same
>> >as the normal pause (i.e. either resuming pause or dropping), I find
>> >it OK to take the original approach.
>> Thank you for the review.
>> I think that I should resend the original patch.
>
>Let's wait a bit for other opinions. We may add rather a new flag
>instead of introducing a new state, too, for example.
>
>Also, I'm not sure about any side-effect to drivers that expect the
>pause only during the running state. We might need some check for a
>capability flag?
Ok. I will wait for more opinion and then resend fixed patch.
>
>In anyway, the timing is bad; it's too late for 5.10 to apply such a
>core change. Can we postpone this for 5.11?
No problem. Actually I need this patch on 5.4 stable.
>
>
>thanks,
>
>Takashi
>
>
>> Am I right?
>> >
>> >
>> >thanks,
>> >
>> >Takashi
>> >
>> >> With a stream with low bitrate, user can't pause or resume the stream
>> >> near the end of the stream because current ALSA doesn't allow it.
>> >> If the stream has very low bitrate enough to store whole stream into
>> >> the buffer, user can't do anything except stop the stream and then
>> >> restart it from first.
>> >> If pause, resume are allowed during draining, user experience can be
>> >> enhanced.
>> >>
>> >> New state for pause during draining is defined in compress_offload.h for
>> >> now. If PCM_STATEs in uapi/sound/asound.h is changed, pcm libraries and
>> >> userspace application will be affected.
>> >>
>> >> Signed-off-by: Gyeongtaek Lee <gt82.lee at samsung.com>
>> >> Cc: stable at vger.kernel.org
>> >> ---
>> >> include/uapi/sound/compress_offload.h | 3 ++
>> >> sound/core/compress_offload.c | 47 ++++++++++++++++++++++-----
>> >> 2 files changed, 41 insertions(+), 9 deletions(-)
>> >>
>> >> diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
>> >> index 7184265c0b0d..f30b9851d1d7 100644
>> >> --- a/include/uapi/sound/compress_offload.h
>> >> +++ b/include/uapi/sound/compress_offload.h
>> >> @@ -189,4 +189,7 @@ struct snd_compr_metadata {
>> >> #define SND_COMPR_TRIGGER_DRAIN 7 /*FIXME move this to pcm.h */
>> >> #define SND_COMPR_TRIGGER_NEXT_TRACK 8
>> >> #define SND_COMPR_TRIGGER_PARTIAL_DRAIN 9
>> >> +
>> >> +/* FIXME move this to asound.h */
>> >> +#define SNDRV_PCM_STATE_DRAINING_PAUSED (SNDRV_PCM_STATE_LAST + 1)
>> >> #endif
>> >> diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
>> >> index 0e53f6f31916..58fbe0d99431 100644
>> >> --- a/sound/core/compress_offload.c
>> >> +++ b/sound/core/compress_offload.c
>> >> @@ -151,6 +151,7 @@ static int snd_compr_free(struct inode *inode, struct file *f)
>> >> case SNDRV_PCM_STATE_RUNNING:
>> >> case SNDRV_PCM_STATE_DRAINING:
>> >> case SNDRV_PCM_STATE_PAUSED:
>> >> + case SNDRV_PCM_STATE_DRAINING_PAUSED:
>> >> data->stream.ops->trigger(&data->stream, SNDRV_PCM_TRIGGER_STOP);
>> >> break;
>> >> default:
>> >> @@ -431,6 +432,7 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait)
>> >> case SNDRV_PCM_STATE_RUNNING:
>> >> case SNDRV_PCM_STATE_PREPARED:
>> >> case SNDRV_PCM_STATE_PAUSED:
>> >> + case SNDRV_PCM_STATE_DRAINING_PAUSED:
>> >> if (avail >= stream->runtime->fragment_size)
>> >> retval = snd_compr_get_poll(stream);
>> >> break;
>> >> @@ -708,11 +710,23 @@ static int snd_compr_pause(struct snd_compr_stream *stream)
>> >> {
>> >> int retval;
>> >>
>> >> - if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING)
>> >> + switch (stream->runtime->state) {
>> >> + case SNDRV_PCM_STATE_RUNNING:
>> >> + retval = stream->ops->trigger(stream,
>> >> + SNDRV_PCM_TRIGGER_PAUSE_PUSH);
>> >> + if (!retval)
>> >> + stream->runtime->state = SNDRV_PCM_STATE_PAUSED;
>> >> + break;
>> >> + case SNDRV_PCM_STATE_DRAINING:
>> >> + retval = stream->ops->trigger(stream,
>> >> + SNDRV_PCM_TRIGGER_PAUSE_PUSH);
>> >> + if (!retval)
>> >> + stream->runtime->state =
>> >> + SNDRV_PCM_STATE_DRAINING_PAUSED;
>> >> + break;
>> >> + default:
>> >> return -EPERM;
>> >> - retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_PAUSE_PUSH);
>> >> - if (!retval)
>> >> - stream->runtime->state = SNDRV_PCM_STATE_PAUSED;
>> >> + }
>> >> return retval;
>> >> }
>> >>
>> >> @@ -720,11 +734,22 @@ static int snd_compr_resume(struct snd_compr_stream *stream)
>> >> {
>> >> int retval;
>> >>
>> >> - if (stream->runtime->state != SNDRV_PCM_STATE_PAUSED)
>> >> + switch (stream->runtime->state) {
>> >> + case SNDRV_PCM_STATE_PAUSED:
>> >> + retval = stream->ops->trigger(stream,
>> >> + SNDRV_PCM_TRIGGER_PAUSE_RELEASE);
>> >> + if (!retval)
>> >> + stream->runtime->state = SNDRV_PCM_STATE_RUNNING;
>> >> + break;
>> >> + case SNDRV_PCM_STATE_DRAINING_PAUSED:
>> >> + retval = stream->ops->trigger(stream,
>> >> + SNDRV_PCM_TRIGGER_PAUSE_RELEASE);
>> >> + if (!retval)
>> >> + stream->runtime->state = SNDRV_PCM_STATE_DRAINING;
>> >> + break;
>> >> + default:
>> >> return -EPERM;
>> >> - retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_PAUSE_RELEASE);
>> >> - if (!retval)
>> >> - stream->runtime->state = SNDRV_PCM_STATE_RUNNING;
>> >> + }
>> >> return retval;
>> >> }
>> >>
>> >> @@ -835,7 +860,9 @@ static int snd_compress_wait_for_drain(struct snd_compr_stream *stream)
>> >> */
>> >>
>> >> ret = wait_event_interruptible(stream->runtime->sleep,
>> >> - (stream->runtime->state != SNDRV_PCM_STATE_DRAINING));
>> >> + (stream->runtime->state != SNDRV_PCM_STATE_DRAINING) &&
>> >> + (stream->runtime->state !=
>> >> + SNDRV_PCM_STATE_DRAINING_PAUSED));
>> >> if (ret == -ERESTARTSYS)
>> >> pr_debug("wait aborted by a signal\n");
>> >> else if (ret)
>> >> @@ -857,6 +884,7 @@ static int snd_compr_drain(struct snd_compr_stream *stream)
>> >> case SNDRV_PCM_STATE_SETUP:
>> >> case SNDRV_PCM_STATE_PREPARED:
>> >> case SNDRV_PCM_STATE_PAUSED:
>> >> + case SNDRV_PCM_STATE_DRAINING_PAUSED:
>> >> return -EPERM;
>> >> case SNDRV_PCM_STATE_XRUN:
>> >> return -EPIPE;
>> >> @@ -909,6 +937,7 @@ static int snd_compr_partial_drain(struct snd_compr_stream *stream)
>> >> case SNDRV_PCM_STATE_SETUP:
>> >> case SNDRV_PCM_STATE_PREPARED:
>> >> case SNDRV_PCM_STATE_PAUSED:
>> >> + case SNDRV_PCM_STATE_DRAINING_PAUSED:
>> >> return -EPERM;
>> >> case SNDRV_PCM_STATE_XRUN:
>> >> return -EPIPE;
>> >>
>> >> base-commit: a1b8638ba1320e6684aa98233c15255eb803fac7
>> >> --
>> >> 2.21.0
>> >>
>> >>
>> >
>>
>
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