On Fri, 09 Jun 2023 17:04:16 +0200, Srinivas Kandagatla wrote: > > For gapless playback it is possible that each track can have different > codec profile with same decoder, for example we have WMA album, > we may have different tracks as WMA v9, WMA v10 and so on > > Or if DSP's like QDSP have abililty to switch decoders on single stream > for each track, then this call could be used to set new codec parameters. > > Existing code does not allow to change this profile while doing gapless > playback. > > Reuse existing SNDRV_COMPRESS_SET_PARAMS to set this new track params along > some additional checks to enforce proper state machine. > > With this new changes now the user can call SNDRV_COMPRESS_SET_PARAMS > anytime after setting next track and additional check in write should > also ensure that params are set before writing new data. > > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> > --- > Changes since v1/RFC: > - removed introduction of new IOCTL, as suggested. > - update the state-machine doc. > > .../sound/designs/compress-offload.rst | 52 +++++++++---------- > sound/core/compress_offload.c | 10 ++-- > 2 files changed, 33 insertions(+), 29 deletions(-) > > diff --git a/Documentation/sound/designs/compress-offload.rst b/Documentation/sound/designs/compress-offload.rst > index 935f325dbc77..205cadcabe70 100644 > --- a/Documentation/sound/designs/compress-offload.rst > +++ b/Documentation/sound/designs/compress-offload.rst > @@ -256,32 +256,32 @@ Gapless Playback SM > For Gapless, we move from running state to partial drain and back, along > with setting of meta_data and signalling for next track :: > > - > - +----------+ > - compr_drain_notify() | | > - +------------------------>| RUNNING | > - | | | > - | +----------+ > - | | > - | | > - | | compr_next_track() > - | | > - | V > - | +----------+ > - | | | > - | |NEXT_TRACK| > - | | | > - | +----------+ > - | | > - | | > - | | compr_partial_drain() > - | | > - | V > - | +----------+ > - | | | > - +------------------------ | PARTIAL_ | > - | DRAIN | > - +----------+ > + +----------+ > + compr_drain_notify() | | compr_set_params() iff next-track set. > + +------------------------>| RUNNING |----------------------+ > + | | | | > + | +----------+ | > + | | | > + | | | > + | | compr_next_track() | > + | | V > + | V | > + | +----------+ | > + | | | | > + | |NEXT_TRACK| | > + | | | | > + | +----------+ | > + | | | > + | +----------------------------+ > + | | > + | | compr_partial_drain() > + | | > + | V > + | +----------+ > + | | | > + +------------------------ | PARTIAL_ | > + | DRAIN | > + +----------+ > > Not supported > ============= > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c > index 243acad89fd3..fe67228e74b3 100644 > --- a/sound/core/compress_offload.c > +++ b/sound/core/compress_offload.c > @@ -294,6 +294,9 @@ static ssize_t snd_compr_write(struct file *f, const char __user *buf, > case SNDRV_PCM_STATE_SETUP: > case SNDRV_PCM_STATE_PREPARED: > case SNDRV_PCM_STATE_RUNNING: > + /* Make sure next track params are set before writing new data */ > + if (stream->next_track) > + return -EPERM; Hm, does this logic correctly match with the comment above? Also, this misses the mutex unlock. thanks, Takashi
