diff mbox series

[5/5] pcm: Update pcm->avail_min with needed_slave_avail_min, after reading unaligned frames

Message ID 1556609923-14093-5-git-send-email-vanitha.channaiah@in.bosch.com (mailing list archive)
State New, archived
Headers show
Series [1/5] pcm: direct: Add generic hw_ptr_alignment function for dmix, dshare and dsnoop | expand

Commit Message

Channaiah Vanitha (RBEI/ECF3) April 30, 2019, 7:38 a.m. UTC 
From: Vanitha Channaiah <vanitha.channaiah@in.bosch.com>

Issue: After partial read of unaligned frames, snd_pcm_wait()
would block for the pcm->avail_min which would result in
blocking of snd_pcm_wait() for longer periods i.e more than
one period as specified by avail_min

Fix: After reading unaligned frames, set the pcm->avail_min
to the needed available frames so that snd_pcm_wait() blocks till
needed available frames.
Once needed available frames are read, set back the original
pcm->avail_min

Signed-off-by: Vanitha Channaiah <vanitha.channaiah@in.bosch.com>
---
 src/pcm/pcm.c       | 21 +++++++++++++++++++++
 src/pcm/pcm_local.h |  2 ++
 2 files changed, 23 insertions(+)

Comments

Takashi Iwai May 2, 2019, 4:01 p.m. UTC | #1 
On Tue, 30 Apr 2019 09:38:43 +0200,
<vanitha.channaiah@in.bosch.com> wrote:
> 
> From: Vanitha Channaiah <vanitha.channaiah@in.bosch.com>
> 
> Issue: After partial read of unaligned frames, snd_pcm_wait()
> would block for the pcm->avail_min which would result in
> blocking of snd_pcm_wait() for longer periods i.e more than
> one period as specified by avail_min
> 
> Fix: After reading unaligned frames, set the pcm->avail_min
> to the needed available frames so that snd_pcm_wait() blocks till
> needed available frames.
> Once needed available frames are read, set back the original
> pcm->avail_min
> 
> Signed-off-by: Vanitha Channaiah <vanitha.channaiah@in.bosch.com>

This kind of changes in the core code should be avoided as much as
possible, especially if it's only relevant with the specific plugins.

Sorry, this isn't convincing enough.  If this is a MUST, please
clarify better.


thanks,

Takashi
diff mbox series

Patch

diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index f0db545..f361eb1 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -973,6 +973,7 @@  int snd_pcm_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t *params)
 		__snd_pcm_unlock(pcm);
 		return err;
 	}
+	pcm->original_avail_min = pcm->avail_min;
 	__snd_pcm_unlock(pcm);
 	return 0;
 }
@@ -7267,6 +7268,17 @@  void snd_pcm_areas_from_bufs(snd_pcm_t *pcm, snd_pcm_channel_area_t *areas,
 	snd_pcm_unlock(pcm);
 }
 
+static void snd_pcm_set_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail)
+{
+	if (avail != pcm->avail_min) {
+		snd_pcm_sw_params_t swparams;
+
+		snd_pcm_sw_params_current(pcm, &swparams);
+		swparams.avail_min = avail;
+		_snd_pcm_sw_params_internal(pcm, &swparams);
+	}
+}
+
 snd_pcm_sframes_t snd_pcm_read_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_t *areas,
 				     snd_pcm_uframes_t offset, snd_pcm_uframes_t size,
 				     snd_pcm_xfer_areas_func_t func)
@@ -7274,6 +7286,7 @@  snd_pcm_sframes_t snd_pcm_read_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_
 	snd_pcm_uframes_t xfer = 0;
 	snd_pcm_sframes_t err = 0;
 	snd_pcm_state_t state;
+	snd_pcm_uframes_t needed_slave_avail_min = 0;
 
 	if (size == 0)
 		return 0;
@@ -7332,6 +7345,14 @@  snd_pcm_sframes_t snd_pcm_read_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_
 		if (err < 0)
 			break;
 		frames = err;
+		pcm->unaligned_frames += frames;
+		pcm->unaligned_frames %= pcm->period_size;
+		if (pcm->unaligned_frames) {
+			needed_slave_avail_min = pcm->period_size - pcm->unaligned_frames;
+			snd_pcm_set_avail_min(pcm, needed_slave_avail_min);
+		} else {
+			snd_pcm_set_avail_min(pcm, pcm->original_avail_min);
+		}
 		offset += frames;
 		size -= frames;
 		xfer += frames;
diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h
index e103f72..3fdffb4 100644
--- a/src/pcm/pcm_local.h
+++ b/src/pcm/pcm_local.h
@@ -210,6 +210,8 @@  struct _snd_pcm {
 	snd_pcm_tstamp_type_t tstamp_type;	/* timestamp type */
 	unsigned int period_step;
 	snd_pcm_uframes_t avail_min;	/* min avail frames for wakeup */
+	snd_pcm_uframes_t unaligned_frames;
+	snd_pcm_uframes_t original_avail_min;
 	int period_event;
 	snd_pcm_uframes_t start_threshold;
 	snd_pcm_uframes_t stop_threshold;