[PATCH v24 02/16] ALSA: pcm: report partial progress under the stream lock

[Joonho Lee]

Allow a driver to publish subperiod progress under the PCM stream lock
without generating a period timer notification. Use the ordinary pointer
update, XRUN and wakeup path. Capture DRAINING can publish its final
tail while playback and other inactive states retain their existing
behavior.

Assisted-by: LLM
Signed-off-by: Joonho Lee <mynameisjune111@xxxxxxxxx>

---
include/sound/pcm.h  |    1 +
 sound/core/pcm_lib.c |   24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -1182,6 +1182,7 @@
 int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
 		      unsigned int cmd, void *arg);                      
 void snd_pcm_period_elapsed_under_stream_lock(struct snd_pcm_substream *substream);
+void snd_pcm_progress_under_stream_lock(struct snd_pcm_substream *substream);
 void snd_pcm_period_elapsed(struct snd_pcm_substream *substream);
 snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
 				     void *buf, bool interleaved,
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1919,6 +1919,30 @@
 EXPORT_SYMBOL(snd_pcm_period_elapsed_under_stream_lock);
 
 /**
+ * snd_pcm_progress_under_stream_lock - Report progress without a period IRQ
+ * @substream: PCM substream
+ *
+ * Context: PCM stream lock held, with no driver pointer or trigger locks held.
+ * Updates the pointer and wakes readers for partial-period transfers. Capture
+ * streams may report their final tail while DRAINING. Unlike a period
+ * notification, this does not imply an elapsed period or tick the PCM timer.
+ * The same pointer, trigger and timestamp callbacks may be invoked.
+ */
+void snd_pcm_progress_under_stream_lock(struct snd_pcm_substream *substream)
+{
+	if (PCM_RUNTIME_CHECK(substream))
+		return;
+	if (!snd_pcm_running(substream) &&
+	    !(substream->stream == SNDRV_PCM_STREAM_CAPTURE &&
+	      substream->runtime->state == SNDRV_PCM_STATE_DRAINING))
+		return;
+	snd_pcm_update_hw_ptr(substream);
+	snd_kill_fasync(substream->runtime->fasync, SIGIO, POLL_IN);
+}
+EXPORT_SYMBOL_GPL(snd_pcm_progress_under_stream_lock);
+
+
+/**
  * snd_pcm_period_elapsed() - update the status of runtime for the next period by acquiring lock of
  *			      PCM substream.
  * @substream: the instance of PCM substream.