Re: [RFC PATCH] ALSA: compress: add support to change codec profile in gapless playback

[Srinivas Kandagatla]

Thanks Vinod for quick review,

On 02/07/2020 12:36, Vinod Koul wrote:
> Hi Srini,
>
> On 02-07-20, 12:11, Srinivas Kandagatla wrote:
> > For gapless playback its possible that each track can have different
>
> s/its/it is
>
> > codec profile with same decoder, for example we have WMA album,
> > we may have different tracks as WMA v9, WMA v10 and so on
> >
> > Existing code does not allow to change this profile while doing gapless
> > playback.
> >
> > This patch adds new SNDRV_COMPRESS_SET_CODEC_PARAMS IOCTL to allow
> > userspace to set this new parameters required for new codec profile.
>
> Thanks, this looks good and in line with discussions done in Audio uConf
>
> > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > ---
> >   include/sound/compress_driver.h       |  5 +++
> >   include/sound/soc-component.h         |  3 ++
> >   include/sound/soc-dai.h               |  5 +++
> >   include/uapi/sound/compress_offload.h |  1 +
> >   sound/core/compress_offload.c         | 54 ++++++++++++++++++++++++---
> >   sound/soc/soc-compress.c              | 30 +++++++++++++++
> >   sound/soc/soc-dai.c                   | 14 +++++++
>
> Can we split the ALSA changes and ASoC changes to different patches
> please?
>
> Also please post driver support for this API..
Yes, q6dsp gapless patches are the users for this api, I will include
them in next version.

> Lastly, documentation needs update about this call
I will fix these in next version!

> >   7 files changed, 106 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h
> > index 70cbc5095e72..8d23351f7ad7 100644
> > --- a/include/sound/compress_driver.h
> > +++ b/include/sound/compress_driver.h
> > @@ -93,6 +93,9 @@ struct snd_compr_stream {
> >    * @set_params: Sets the compressed stream parameters, mandatory
> >    * This can be called in during stream creation only to set codec params
> >    * and the stream properties
> > + * @set_codec_params: Sets the compressed stream codec parameters, mandatory
>
> This should be optional as gapless is optional
>
> > --- a/include/uapi/sound/compress_offload.h
> > +++ b/include/uapi/sound/compress_offload.h
> > @@ -172,6 +172,7 @@ struct snd_compr_metadata {
> >   						 struct snd_compr_metadata)
> >   #define SNDRV_COMPRESS_GET_METADATA	_IOWR('C', 0x15,\
> >   						 struct snd_compr_metadata)
> > +#define SNDRV_COMPRESS_SET_CODEC_PARAMS	_IOW('C', 0x16, struct snd_codec)
> >   #define SNDRV_COMPRESS_TSTAMP		_IOR('C', 0x20, struct snd_compr_tstamp)
> >   #define SNDRV_COMPRESS_AVAIL		_IOR('C', 0x21, struct snd_compr_avail)
> >   #define SNDRV_COMPRESS_PAUSE		_IO('C', 0x30)
>
> I think we should bump the compress version too for checking in userland
> about this support
Sure!

> >   static int snd_compress_check_input(struct snd_compr_params *params)
> >   {
> >   	/* first let's check the buffer parameter's */
> > @@ -574,14 +586,41 @@ static int snd_compress_check_input(struct snd_compr_params *params)
> >   	    params->buffer.fragments == 0)
> >   		return -EINVAL;
> >   
> > -	/* now codec parameters */
> > -	if (params->codec.id == 0 || params->codec.id > SND_AUDIOCODEC_MAX)
> > -		return -EINVAL;
> > +	return snd_compress_check_codec_params(&params->codec);
>
> Can this be 1st patch to prepare for this change?
>
> >   
> > -	if (params->codec.ch_in == 0 || params->codec.ch_out == 0)
> > -		return -EINVAL;
> > +}
> >   
> > -	return 0;
> > +static int snd_compr_set_codec_params(struct snd_compr_stream *stream,
> > +				      unsigned long arg)
> > +{
> > +	struct snd_codec *params;
> > +	int retval;
> > +
> > +	if (!stream->ops->set_codec_params)
> > +		return -EPERM;
> > +
> > +	if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING)
> > +		return -EPERM;
> > +
> > +	/* codec params can be only set when next track has been signalled */
> > +	if (stream->next_track == false)
> > +		return -EPERM;
> > +
> > +	params = memdup_user((void __user *)arg, sizeof(*params));
> > +	if (IS_ERR(params))
> > +		return PTR_ERR(params);
> > +
> > +	retval = snd_compress_check_codec_params(params);
> > +	if (retval)
> > +		goto out;
> > +
> > +	retval = stream->ops->set_codec_params(stream, params);
> > +	if (retval)
> > +		goto out;
>
> this jump is superfluous
yes, we could just remove the check!

> > +
> > +out:
> > +	kfree(params);
> > +	return retval;
> >   }
>
> ...
>
> > +static int soc_compr_set_codec_params(struct snd_compr_stream *cstream,
> > +				      struct snd_codec *codec)
> > +{
> > +	struct snd_soc_pcm_runtime *rtd = cstream->private_data;
> > +	struct snd_soc_component *component;
> > +	struct snd_soc_dai *cpu_dai = asoc_rtd_to_cpu(rtd, 0);
> > +	int i, ret;
> > +
> > +	mutex_lock_nested(&rtd->card->pcm_mutex, rtd->card->pcm_subclass);
> > +
> > +	ret = snd_soc_dai_compr_set_codec_params(cpu_dai, cstream, codec);
> > +	if (ret < 0)
> > +		goto err;
> > +
> > +	for_each_rtd_components(rtd, i, component) {
> > +		if (!component->driver->compress_ops ||
> > +		    !component->driver->compress_ops->set_codec_params)
> > +			continue;
> > +
> > +		ret = component->driver->compress_ops->set_codec_params(component, cstream,
> > +								     codec);
>
> maybe use a compress_ops pointer to make this look and read better :)

Sure will do that!

--srini

>