* [PATCH] ALSA: pcm: Comment why read blocks when PCM is not running
@ 2019-02-13 2:57 Ricardo Biehl Pasquali
2019-02-13 7:03 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Ricardo Biehl Pasquali @ 2019-02-13 2:57 UTC (permalink / raw)
To: tiwai; +Cc: alsa-devel
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>
---
sound/core/pcm_lib.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index bcb06bd3d..345ab1ab2 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) {
--
2.19.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ALSA: pcm: Comment why read blocks when PCM is not running
2019-02-13 2:57 [PATCH] ALSA: pcm: Comment why read blocks when PCM is not running Ricardo Biehl Pasquali
@ 2019-02-13 7:03 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2019-02-13 7:03 UTC (permalink / raw)
To: Ricardo Biehl Pasquali; +Cc: alsa-devel
On Wed, 13 Feb 2019 03:57:51 +0100,
Ricardo Biehl Pasquali wrote:
>
> 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>
Applied, thanks.
Takashi
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-02-13 2:57 [PATCH] ALSA: pcm: Comment why read blocks when PCM is not running Ricardo Biehl Pasquali
2019-02-13 7:03 ` Takashi Iwai
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