Re: [PATCH] ALSA: compress: allow to leave draining state when pausing in draining

[Takashi Iwai <tiwai@suse.de>]

On Tue, 06 Jul 2021 14:44:40 +0200,
Robert Lee wrote:
> 
> When compress offload pauses in draining state, not all platforms
> need to keep in draining state. Some platforms may call drain or
> partial drain again when resume from pause in draining, so it needs
> to wake up from snd_compress_wait_for_drain() in this case.
> 
> Call API snd_compr_leave_draining_in_pause(), if the platform
> doesn't need to keep in draining state when pause in draining
> state.
> 
> Signed-off-by: Robert Lee <lerobert@google.com>

Well, the logic is a bit confusing (hard to understand what really
"leave-draining-in-pause" actually means) but also error-prone;
e.g. you left pause_in_draining flag set while changing the state to
SNDRV_PCM_STATE_PAUSED.  This will keep the pause_in_draining flag
even after snd_compr_resume() call.


thanks,

Takashi

> ---
>  include/sound/compress_driver.h | 14 ++++++++++++++
>  sound/core/compress_offload.c   |  7 ++++++-
>  2 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h
> index 277087f635f3..e16524a93a14 100644
> --- a/include/sound/compress_driver.h
> +++ b/include/sound/compress_driver.h
> @@ -145,6 +145,7 @@ struct snd_compr_ops {
>   * @lock: device lock
>   * @device: device id
>   * @use_pause_in_draining: allow pause in draining, true when set
> + * @leave_draining_in_pause: leave draining state when pausing in draining
>   */
>  struct snd_compr {
>  	const char *name;
> @@ -156,6 +157,7 @@ struct snd_compr {
>  	struct mutex lock;
>  	int device;
>  	bool use_pause_in_draining;
> +	bool leave_draining_in_pause;
>  #ifdef CONFIG_SND_VERBOSE_PROCFS
>  	/* private: */
>  	char id[64];
> @@ -182,6 +184,18 @@ static inline void snd_compr_use_pause_in_draining(struct snd_compr_stream *subs
>  	substream->device->use_pause_in_draining = true;
>  }
>  
> +/**
> + * snd_compr_leave_draining_in_pause - Leave draining state when pause in draining
> + * @substream: compress substream to set
> + *
> + * In some platform, we need to leave draining state when we use pause in draining.
> + * Add API to allow leave draining state.
> + */
> +static inline void snd_compr_leave_draining_in_pause(struct snd_compr_stream *substream)
> +{
> +	substream->device->leave_draining_in_pause = true;
> +}
> +
>  /* dsp driver callback apis
>   * For playback: driver should call snd_compress_fragment_elapsed() to let the
>   * framework know that a fragment has been consumed from the ring buffer
> diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
> index 21ce4c056a92..9c7bd4db6ecd 100644
> --- a/sound/core/compress_offload.c
> +++ b/sound/core/compress_offload.c
> @@ -719,8 +719,13 @@ static int snd_compr_pause(struct snd_compr_stream *stream)
>  		if (!stream->device->use_pause_in_draining)
>  			return -EPERM;
>  		retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_PAUSE_PUSH);
> -		if (!retval)
> +		if (!retval) {
>  			stream->pause_in_draining = true;
> +			if (stream->device->leave_draining_in_pause) {
> +				stream->runtime->state = SNDRV_PCM_STATE_PAUSED;
> +				wake_up(&stream->runtime->sleep);
> +			}
> +		}
>  		break;
>  	default:
>  		return -EPERM;
> -- 
> 2.32.0.93.g670b81a890-goog
>