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 --- src/pcm/pcm_hw.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c index 43c37b83..aacfa669 100644 --- a/src/pcm/pcm_hw.c +++ b/src/pcm/pcm_hw.c @@ -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) @@ -653,7 +662,7 @@ 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); @@ -1069,7 +1078,7 @@ 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