[PATCH 7/7] ALSA: pcm: Call ack() whenever appl_ptr is updated

Takashi Iwai
2017-05-21T19:02:58Z

Although the ack callback is supposed to be called at each appl_ptr or
hw_ptr update, we missed a few opportunities: namely, forward, rewind
and sync_ptr.

Formerly calling ack at rewind may have leaded to unexpected results
due to the forgotten negative appl_ptr update in indirect-PCM helper,
which is the major user of the PCM ack callback. But now we fixed
this oversights, thus we can call ack callback safely even at rewind
callback -- of course with the proper handling of the error from the
callback.

This patch adds the calls of ack callback in the places mentioned in
the above.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/core/pcm_native.c | 46 +++++++++++++++++++++++++++++++++++++---------
1 file changed, 37 insertions(+), 9 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index ecde57afa45a..7bc4a0bbad6f 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -2455,13 +2455,35 @@ static int do_pcm_hwsync(struct snd_pcm_substream *substream)
}
}

-/* increase the appl_ptr; returns the processed frames */
+/* update to the given appl_ptr and call ack callback if needed;
+ * when an error is returned, take back to the original value
+ */
+static int apply_appl_ptr(struct snd_pcm_substream *substream,
+ snd_pcm_uframes_t appl_ptr)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;
+ int ret;
+
+ runtime->control->appl_ptr = appl_ptr;
+ if (substream->ops->ack) {
+ ret = substream->ops->ack(substream);
+ if (ret < 0) {
+ runtime->control->appl_ptr = old_appl_ptr;
+ return ret;
+ }
+ }
+ return 0;
+}
+
+/* increase the appl_ptr; returns the processed frames or a negative error */
static snd_pcm_sframes_t forward_appl_ptr(struct snd_pcm_substream *substream,
snd_pcm_uframes_t frames,
snd_pcm_sframes_t avail)
{
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_sframes_t appl_ptr;
+ int ret;

if (avail <= 0)
return 0;
@@ -2470,17 +2492,18 @@ static snd_pcm_sframes_t forward_appl_ptr(struct snd_pcm_substream *substream,
appl_ptr = runtime->control->appl_ptr + frames;
if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
appl_ptr -= runtime->boundary;
- runtime->control->appl_ptr = appl_ptr;
- return frames;
+ ret = apply_appl_ptr(substream, appl_ptr);
+ return ret < 0 ? ret : frames;
}

-/* decrease the appl_ptr; returns the processed frames */
+/* decrease the appl_ptr; returns the processed frames or a negative error */
static snd_pcm_sframes_t rewind_appl_ptr(struct snd_pcm_substream *substream,
snd_pcm_uframes_t frames,
snd_pcm_sframes_t avail)
{
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_sframes_t appl_ptr;
+ int ret;

if (avail <= 0)
return 0;
@@ -2489,8 +2512,8 @@ static snd_pcm_sframes_t rewind_appl_ptr(struct snd_pcm_substream *substream,
appl_ptr = runtime->control->appl_ptr - frames;
if (appl_ptr < 0)
appl_ptr += runtime->boundary;
- runtime->control->appl_ptr = appl_ptr;
- return frames;
+ ret = apply_appl_ptr(substream, appl_ptr);
+ return ret < 0 ? ret : frames;
}

static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *substream,
@@ -2620,10 +2643,15 @@ static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
return err;
}
snd_pcm_stream_lock_irq(substream);
- if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL))
- control->appl_ptr = sync_ptr.c.control.appl_ptr;
- else
+ if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) {
+ err = apply_appl_ptr(substream, sync_ptr.c.control.appl_ptr);
+ if (err < 0) {
+ snd_pcm_stream_unlock_irq(substream);
+ return err;
+ }
+ } else {
sync_ptr.c.control.appl_ptr = control->appl_ptr;
+ }
if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_AVAIL_MIN))
control->avail_min = sync_ptr.c.control.avail_min;
else
--
2.13.0