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pcm: direct: check state before enter poll on timer

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To avoid the chances of timeout, we need to check the enter poll
in state xrun.

Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
Signed-off-by: Mounesh Sutar <mounesh_sutar@mentor.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Andreas Pape 2017-01-10 12:03:54 +05:30 • committed by Takashi Iwai
parent 1a9bd0f044
commit 789ee39727
5 changed files with 63 additions and 6 deletions
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40
src/pcm/pcm_direct.c
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@ -645,6 +645,46 @@ int snd_pcm_direct_client_chk_xrun(snd_pcm_direct_t *direct, snd_pcm_t *pcm)
return 0;
}
/*
* This is the only operation guaranteed to be called before entering poll().
* Direct plugins use fd of snd_timer to poll on, these timers do NOT check
* state of substream in kernel by intention.
* Only the enter to xrun might be notified once (SND_TIMER_EVENT_MSTOP).
* If xrun event was not correctly handled or was ignored it will never be
* evaluated again afterwards.
* This will result in snd_pcm_wait() always returning timeout.
* In contrast poll() on pcm hardware checks ALSA state and will immediately
* return POLLERR on XRUN.
*
* To prevent timeout and applications endlessly spinning without xrun
* detected we add a state check here which may trigger the xrun sequence.
*
* return count of filled descriptors or negative error code
*/
int snd_pcm_direct_poll_descriptors(snd_pcm_t *pcm, struct pollfd *pfds,
unsigned int space)
{
if (pcm->poll_fd < 0) {
SNDMSG("poll_fd < 0");
return -EIO;
}
if (space >= 1 && pfds) {
pfds->fd = pcm->poll_fd;
pfds->events = pcm->poll_events | POLLERR | POLLNVAL;
} else {
return 0;
}
/* this will also evaluate slave state and enter xrun if necessary */
switch (snd_pcm_state(pcm)) {
case SND_PCM_STATE_XRUN:
return -EPIPE;
default:
break;
}
return 1;
}
int snd_pcm_direct_poll_revents(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
{
snd_pcm_direct_t *dmix = pcm->private_data;