[alsa-devel] [RFC 4/5] compress: add the core file

[Dimitris Papastamos]

On Fri, Sep 02, 2011 at 11:36:24AM +0530, Vinod Koul wrote:
> This patch ads core.c, the file which implements the ioctls and
> registers the devices
> 
> Signed-off-by: Vinod Koul <vinod.koul at linux.intel.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> ---
>  sound/compress_offload/core.c |  632 +++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 632 insertions(+), 0 deletions(-)
>  create mode 100644 sound/compress_offload/core.c
> 
> diff --git a/sound/compress_offload/core.c b/sound/compress_offload/core.c
> new file mode 100644
> index 0000000..1797dba
> --- /dev/null
> +++ b/sound/compress_offload/core.c
> @@ -0,0 +1,632 @@

> +unsigned int snd_compr_poll(struct file *f, poll_table *wait)
> +{
> +	struct snd_ioctl_data *data = f->private_data;
> +	struct snd_compr_stream *stream;
> +
> +	BUG_ON(!data);
> +	stream = &data->stream;
> +
> +	if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING)
> +		return -ENXIO;
> +	poll_wait(f, &stream->runtime->sleep, wait);
> +
> +	/* this would change after read is implemented, we would need to
> +	 * check for direction here */
> +	if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING)
> +		return POLLOUT | POLLWRNORM;
> +
> +	return 0;
> +}

Do we need to grab any locks here?  I'm also confused about checking for
!= SNDRV_PCM_STATE_RUNNING and only then returning POLLOUT | POLLWRNORM.
Shouldn't the normal cycle be write->start->poll->write->poll->...?  At
the moment, the state won't change and for this cycle to be effective we
have to call stop/drain in between.  Am I missing something?

Thanks,
Dimitris