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

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Date:   Thu, 8 Jul 2021 10:22:46 +0800
From:   Robert Lee <lerobert@...gle.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     vkoul@...nel.org, perex@...ex.cz, tiwai@...e.com,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        carterhsu@...gle.com, zxinhui@...gle.com, bubblefang@...gle.com
Subject: Re: [PATCH] ALSA: compress: allow to leave draining state when
 pausing in draining

Hi Takashi,
Nice catch. I make a change and mail patch v2 for reviewing.

thanks,
Robert.


Takashi Iwai <tiwai@...e.de> 於 2021年7月7日 週三 下午7:38寫道：
>
> 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@...gle.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
> >