Revert "CRAS: cras_alsa_io - Increase appl_ptr when underrun happens"

This reverts commit ac429fff80faaf1768332858f0e483379ea6f1aa.

This CL is causing grunt audio to stutter on resume from S3 when
playing an audio file from local disk.

BUG=b:117302276
TEST=Deploy to grunt or careena
TEST=Sign in to DUT, save an audio file to "My Files > Downloads"
TEST=Start playing audio file
TEST=Enter S3 (ie, powerd_dbus_suspend)
 => No stuttering after resume (confirm at least 30 seconds)

Change-Id: I442ed3bfcb86ae8c46cf8a9cc3d2ebb0674adadf
Reviewed-on: https://chromium-review.googlesource.com/1272064
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>

2 files changed, 12 insertions, 29 deletions

diff --git a/cras/src/server/cras_alsa_io.c b/cras/src/server/cras_alsa_io.c
index 3dafb50e..d9169f16 100644
--- a/cras/src/server/cras_alsa_io.c
+++ b/cras/src/server/cras_alsa_io.c
@@ -1734,31 +1734,16 @@ static int fill_whole_buffer_with_zeros(struct cras_iodev *iodev)
 	return 0;
 }
 
-/*
- * Move appl_ptr to min_buffer_level + min_cb_level frames ahead of hw_ptr
- * when resuming from free run.
- */
-static int adjust_appl_ptr_for_leaving_free_run(struct cras_iodev *odev)
-{
-	struct alsa_io *aio = (struct alsa_io *)odev;
-	snd_pcm_uframes_t ahead;
-
-	ahead = odev->min_buffer_level + odev->min_cb_level;
-	return cras_alsa_resume_appl_ptr(aio->handle, ahead);
-}
-
-/*
- * Move appl_ptr to min_buffer_level + min_cb_level * 1.5 frames ahead of
- * hw_ptr when adjusting appl_ptr from underrun.
- */
-static int adjust_appl_ptr_for_underrun(struct cras_iodev *odev)
+static int adjust_appl_ptr(struct cras_iodev *odev)
 {
 	struct alsa_io *aio = (struct alsa_io *)odev;
-	snd_pcm_uframes_t ahead;
 
-	ahead = odev->min_buffer_level + odev->min_cb_level +
-		odev->min_cb_level / 2;
-	return cras_alsa_resume_appl_ptr(aio->handle, ahead);
+	/* Move appl_ptr to min_buffer_level + min_cb_level frames ahead of
+	 * hw_ptr when resuming from free run or adjusting appl_ptr from
+	 * underrun. */
+	return cras_alsa_resume_appl_ptr(
+			aio->handle,
+			odev->min_buffer_level + odev->min_cb_level);
 }
 
 /* This function is for leaving no-stream state but still not in free run yet.
@@ -1816,7 +1801,7 @@ static int alsa_output_underrun(struct cras_iodev *odev)
 	if (rc)
 		return rc;
 	/* Adjust appl_ptr to leave underrun. */
-	return adjust_appl_ptr_for_underrun(odev);
+	return adjust_appl_ptr(odev);
 }
 
 static int possibly_enter_free_run(struct cras_iodev *odev)
@@ -1874,7 +1859,7 @@ static int leave_free_run(struct cras_iodev *odev)
 	int rc;
 
 	if (aio->is_free_running)
-		rc = adjust_appl_ptr_for_leaving_free_run(odev);
+		rc = adjust_appl_ptr(odev);
 	else
 		rc = adjust_appl_ptr_samples_remaining(odev);
 	if (rc) {
diff --git a/cras/src/tests/alsa_io_unittest.cc b/cras/src/tests/alsa_io_unittest.cc
index 26c3232f..9a6b7f62 100644
--- a/cras/src/tests/alsa_io_unittest.cc
+++ b/cras/src/tests/alsa_io_unittest.cc
@@ -2215,7 +2215,6 @@ TEST_F(AlsaFreeRunTestSuite, LeaveFreeRunInFreeRun) {
 TEST_F(AlsaFreeRunTestSuite, OutputUnderrun) {
   int rc;
   int16_t *zeros;
-  snd_pcm_uframes_t offset;
 
   aio.num_underruns = 0;
 
@@ -2228,12 +2227,11 @@ TEST_F(AlsaFreeRunTestSuite, OutputUnderrun) {
   zeros = (int16_t *)calloc(BUFFER_SIZE * 2, sizeof(*zeros));
   EXPECT_EQ(0, memcmp(zeros, cras_alsa_mmap_begin_buffer, BUFFER_SIZE * 2 * 2));
 
-  // appl_ptr should be moved to min_buffer_level + 1.5 * min_cb_level ahead of
+  // appl_ptr should be moved to min_buffer_level + min_cb_level ahead of
   // hw_ptr.
-  offset = aio.base.min_buffer_level + aio.base.min_cb_level +
-	   aio.base.min_cb_level / 2;
   EXPECT_EQ(1, cras_alsa_resume_appl_ptr_called);
-  EXPECT_EQ(offset, cras_alsa_resume_appl_ptr_ahead);
+  EXPECT_EQ(aio.base.min_buffer_level + aio.base.min_cb_level,
+            cras_alsa_resume_appl_ptr_ahead);
 
   free(zeros);
 }