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pcm: hw: add a helper function to issue appl_ptr without side-effects

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After starting, PCM substream shift its state to running and applications
can move appl_ptr by several ways. When status and control data of runtime
of the PCM substream is not mapped, the applications should issue appl_ptr
to kernel land. In this case, when any PCM frames is handled by mmap
operation, the applications should issue appl_ptr to update.

This commit adds a helper function for this purpose. To avoid unexpected
change of avail_min, this commit uses a flag just to update appl_ptr.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2017-06-30 20:37:27 +09:00 • committed by Takashi Iwai
parent 8a3df40bce
commit de9fe69e40
1 changed files with 11 additions and 2 deletions
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13
src/pcm/pcm_hw.c
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@ -151,6 +151,15 @@ static int sync_ptr(snd_pcm_hw_t *hw, unsigned int flags)
return 0;
}
static int issue_applptr(snd_pcm_hw_t *hw)
{
if (!hw->mmap_control_fallbacked)
return 0;
/* Avoid unexpected change of avail_min in kernel space. */
return sync_ptr1(hw, SNDRV_PCM_SYNC_PTR_AVAIL_MIN);
}
static int request_hwsync(snd_pcm_hw_t *hw)
{
if (!hw->mmap_status_fallbacked)
@ -667,7 +676,7 @@ static int snd_pcm_hw_start(snd_pcm_t *pcm)
assert(pcm->stream != SND_PCM_STREAM_PLAYBACK ||
snd_pcm_mmap_playback_hw_avail(pcm) > 0);
#endif
sync_ptr(hw, 0);
issue_applptr(hw);
if (ioctl(hw->fd, SNDRV_PCM_IOCTL_START) < 0) {
err = -errno;
SYSMSG("SNDRV_PCM_IOCTL_START failed (%i)", err);
@ -1081,7 +1090,7 @@ static snd_pcm_sframes_t snd_pcm_hw_mmap_commit(snd_pcm_t *pcm,
snd_pcm_hw_t *hw = pcm->private_data;
snd_pcm_mmap_appl_forward(pcm, size);
sync_ptr(hw, 0);
issue_applptr(hw);
#ifdef DEBUG_MMAP
fprintf(stderr, "appl_forward: hw_ptr = %li, appl_ptr = %li, size = %li\n", *pcm->hw.ptr, *pcm->appl.ptr, size);
#endif