Hi,
On Apr 16 2018 21:14, Takashi Iwai wrote:
Yet another slight code cleanup: there are two places where
calculating the PCM delay, and they can be unified in a single
helper. It reduces the multiple open codes.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
sound/core/pcm_native.c | 36 +++++++++++++++---------------------
1 file changed, 15 insertions(+), 21 deletions(-)
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index eddb0cd6d1eb..81bbe0b3284b 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -857,6 +857,18 @@ static int snd_pcm_sw_params_user(struct snd_pcm_substream *substream,
return err;
}
+static inline snd_pcm_uframes_t
+snd_pcm_calc_delay(struct snd_pcm_substream *substream)
+{
+ snd_pcm_uframes_t delay;
+
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ delay = snd_pcm_playback_hw_avail(substream->runtime);
+ else
+ delay = snd_pcm_capture_avail(substream->runtime);
+ return delay + substream->runtime->delay;
+}
+
int snd_pcm_status(struct snd_pcm_substream *substream,
struct snd_pcm_status *status)
{
@@ -909,19 +921,7 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
status->appl_ptr = runtime->control->appl_ptr;
status->hw_ptr = runtime->status->hw_ptr;
status->avail = snd_pcm_avail(substream);
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
- if (runtime->status->state == SNDRV_PCM_STATE_RUNNING ||
- runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
- status->delay = runtime->buffer_size - status->avail;
- status->delay += runtime->delay;
- } else
- status->delay = 0;
- } else {
- if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
- status->delay = status->avail + runtime->delay;
- else
- status->delay = 0;
- }
+ status->delay = snd_pcm_calc_delay(substream);
status->avail_max = runtime->avail_max;
status->overrange = runtime->overrange;
runtime->avail_max = 0;
@@ -2655,19 +2655,13 @@ static int snd_pcm_hwsync(struct snd_pcm_substream *substream)
static snd_pcm_sframes_t snd_pcm_delay(struct snd_pcm_substream *substream)
{
- struct snd_pcm_runtime *runtime = substream->runtime;
int err;
snd_pcm_sframes_t n = 0;
snd_pcm_stream_lock_irq(substream);
err = do_pcm_hwsync(substream);
- if (!err) {
- if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
- n = snd_pcm_playback_hw_avail(runtime);
- else
- n = snd_pcm_capture_avail(runtime);
- n += runtime->delay;
- }
+ if (!err)
+ n = snd_pcm_calc_delay(substream);
snd_pcm_stream_unlock_irq(substream);
return err < 0 ? err : n;
}
When any PCM substream is under running state, this patchset is good.
Below is short descriptions of calculation in each case.
snd_pcm_status() for playback on running
* delay = runtime->buffer_size - status->avail
(=snd_pcm_playback_hw_avail())
* delay += runtime->delay
snd_pcm_status() for capture on running
* delay = status->avail (= snd_pcm_avail() = snd_pcm_capture_avail())
* delay += runtime->delay
snd_pcm_delay() for playback
* delay = snd_pcm_playback_hw_avail()
* delay += rutime_delay
snd_pcm_delay() for capture
* delay = snd_pcm_capture_avail(runtime)
* delay += runtime->delay
However, under non-running states, I have some suspicion, because
originally 'snd_pcm_status()' take 0 in the states while your code
manage to calculate it.
(sound/core/pcm_native.c)
911 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
912 status->avail = snd_pcm_playback_avail(runtime);
913 if (runtime->status->state == SNDRV_PCM_STATE_RUNNING ||
914 runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
...
917 } else
918 status->delay = 0;
919 } else {
920 status->avail = snd_pcm_capture_avail(runtime);
921 if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
...
923 else
924 status->delay = 0;
925 }
I think this patch is based on an assumption that hw_ptr is zeroed
after stopping PCM substream. On the other hand, I cannot find codes
which reset hw_ptr to zero during lifetime of PCM runtime. Any
calculation of delay with hw_ptr could return non-zero value in
non-running states. This patch can change behaviour of PCM core in a
view of userspace applications, in my understanding.
Regards
Takashi Sakamoto
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