On Wed, 28 Mar 2018 10:42:50 +0200,
Wischer, Timo (ADITG/ESB) wrote:
>
> @@ -67,6 +73,12 @@ static void snd_pcm_ioplug_hw_ptr_update(snd_pcm_t *pcm)
> delta = wrap_point + hw - io->last_hw;
> }
> snd_pcm_mmap_hw_forward(io->data->pcm, delta);
> + /* stop the stream if all samples are drained */
> + if (io->data->state == SND_PCM_STATE_DRAINING) {
> + avail = snd_pcm_mmap_avail(pcm);
> + if (avail >= pcm->buffer_size)
> + snd_pcm_ioplug_drop(pcm);
> + }
> io->last_hw = (snd_pcm_uframes_t)hw;
> } else
> io->data->state = SNDRV_PCM_STATE_XRUN;
> In case of draining drop has to be called because draining is done
OK, makes sense.
> @@ -488,20 +500,66 @@ static int snd_pcm_ioplug_drop(snd_pcm_t *pcm)
> return 0;
> }
>
> +static int ioplug_drain_via_poll(snd_pcm_t *pcm)
> +{
> + ioplug_priv_t *io = pcm->private_data;
> + int err;
> +
> + /* in non-blocking mode, leave application to poll() by itself */
> + if (io->data->nonblock)
> + return -EAGAIN;
> In case of nonblock snd_pcm_ioplug_hw_ptr_update() will not be called by the user
> Therefore the user will never detect that draining is done.
> I fear snd_pcm_ioplug_hw_ptr_update() has also to be called in nonblock mode here.
For the non-blocking mode, it's not supposed that drain() is called
multiple times. Instead, it should do the loop of snd_pcm_wait(), and
status check, as ioplug_drain_vai_poll() actually does.
Yes, it's weird, but it's the standard way for non-blocking mode, even
for the kernel drivers. So, the practical recommendation for draining
is to temporarily switch to blocking mode before calling
snd_pcm_drain().
> Will you create the patch and apply it to master or
> is there anything which I have to do?
I'll cook up the proper patch and submit to ML soon later.
Then it'll be merged to git tree, and you can work on it.
thanks,
Takashi
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
