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| author | Ricardo Biehl Pasquali <pasqualirb@gmail.com> | 2019-02-13 00:57:51 -0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2019-02-13 08:01:05 +0100 |
| commit | 932a81519572156a88dbc2349d183c603446f9c4 (patch) | |
| tree | 0e88452ce44a24650e853d917eb17f7c6ae77585 | |
| parent | 5a23f385686fe0e9cd8e19cb09dff9a3b68082de (diff) | |
| download | linux-932a81519572156a88dbc2349d183c603446f9c4.tar.gz linux-932a81519572156a88dbc2349d183c603446f9c4.tar.bz2 linux-932a81519572156a88dbc2349d183c603446f9c4.zip | |
ALSA: pcm: Comment why read blocks when PCM is not running
This avoids bringing back the problem introduced by
62ba568f7aef ("ALSA: pcm: Return 0 when size <
start_threshold in capture") and fixed in 00a399cad1a0
("ALSA: pcm: Revert capture stream behavior change in
blocking mode"), which prevented the user from starting
capture from another thread.
Signed-off-by: Ricardo Biehl Pasquali <pasqualirb@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
| -rw-r--r-- | sound/core/pcm_lib.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index bcb06bd3d81d..345ab1ab2cac 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -2176,6 +2176,10 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream, if (runtime->status->state == SNDRV_PCM_STATE_RUNNING) snd_pcm_update_hw_ptr(substream); + /* + * If size < start_threshold, wait indefinitely. Another + * thread may start capture + */ if (!is_playback && runtime->status->state == SNDRV_PCM_STATE_PREPARED && size >= runtime->start_threshold) { |