CRAS: iodev - Add function to swap left and right channel using dsp

Add cras_iodev_dsp_set_swap_mode_for_node to swap left and right channel
using dsp. It is used as the default implementation of
set_swap_mode_for_node ops on alsa_io device.

To use this function, there must be a swap_lr section in dsp.ini:

  [swap_lr]
  library=builtin
  label=swap_lr
  disable=swap_lr_disabled
  input_0={swap_lr:0}
  input_1={swap_lr:1}
  output_2={dst:1}
  output_3={dst:0}

where {swap_lr:0}, {swap_lr:1} are the output ports of the block which
was before output sink (usually eq2).

cras_iodev_dsp_set_swap_mode_for_node must support two use cases:
- User sets swap mode when device is not playing.
- User sets swap mode when device is playing.

In the first use case, cras_iodev_update_dsp sets swap_lr_disabled
variable based on left_right_swapped on active node.
For the second use case, we need to udpate dsp in
cras_iodev_dsp_set_swap_mode_for_node so the change takes effect right
away. It is fine to do so because pipeline in the context is protected
by a mutex.

BUG=chromium:645051
TEST=with modified dsp, check left right swap works using
cras_test_client --swap_left_right n:m:1.

Signed-off-by: Cheng-Yi Chiang <cychiang@chromium.org>
Change-Id: I78fa29f3bd9edbe59eda73242cc855aa8781bce0
Reviewed-on: https://chromium-review.googlesource.com/386703
Reviewed-by: Dylan Reid <dgreid@chromium.org>

6 files changed, 65 insertions, 1 deletions

diff --git a/cras/src/server/cras_alsa_io.c b/cras/src/server/cras_alsa_io.c
index c972f3c1..ca9cb59f 100644
--- a/cras/src/server/cras_alsa_io.c
+++ b/cras/src/server/cras_alsa_io.c
@@ -1577,6 +1577,7 @@ struct cras_iodev *alsa_iodev_create(size_t card_index,
 	iodev->get_hotword_models = get_hotword_models;
 	iodev->no_stream = cras_iodev_default_no_stream_playback;
 	iodev->get_num_underruns = get_num_underruns;
+	iodev->set_swap_mode_for_node = cras_iodev_dsp_set_swap_mode_for_node;
 
 	if (card_type == ALSA_CARD_TYPE_USB)
 		iodev->min_buffer_level = USB_EXTRA_BUFFER_FRAMES;
diff --git a/cras/src/server/cras_dsp.c b/cras/src/server/cras_dsp.c
index 7b3df8f7..8052a047 100644
--- a/cras/src/server/cras_dsp.c
+++ b/cras/src/server/cras_dsp.c
@@ -45,6 +45,7 @@ static void initialize_environment(struct cras_expr_env *env)
 	cras_expr_env_set_variable_boolean(env, "disable_eq", 0);
 	cras_expr_env_set_variable_boolean(env, "disable_drc", 0);
 	cras_expr_env_set_variable_string(env, "dsp_name", "");
+	cras_expr_env_set_variable_boolean(env, "swap_lr_disabled", 1);
 }
 
 static struct pipeline *prepare_pipeline(struct cras_dsp_context *ctx)
diff --git a/cras/src/server/cras_iodev.c b/cras/src/server/cras_iodev.c
index 6172fb74..3490ac53 100644
--- a/cras/src/server/cras_iodev.c
+++ b/cras/src/server/cras_iodev.c
@@ -441,15 +441,42 @@ error:
 
 void cras_iodev_update_dsp(struct cras_iodev *iodev)
 {
+	char swap_lr_disabled = 1;
+
 	if (!iodev->dsp_context)
 		return;
 
 	cras_dsp_set_variable_string(iodev->dsp_context, "dsp_name",
 				     iodev->dsp_name ? : "");
 
+	if (iodev->active_node && iodev->active_node->left_right_swapped)
+		swap_lr_disabled = 0;
+
+	cras_dsp_set_variable_boolean(iodev->dsp_context, "swap_lr_disabled",
+				      swap_lr_disabled);
+
 	cras_dsp_load_pipeline(iodev->dsp_context);
 }
 
+
+int cras_iodev_dsp_set_swap_mode_for_node(struct cras_iodev *iodev,
+					   struct cras_ionode *node, int enable)
+{
+	if (node->left_right_swapped == enable)
+		return 0;
+
+	/* Sets left_right_swapped property on the node. It will be used
+	 * when cras_iodev_update_dsp is called. */
+	node->left_right_swapped = enable;
+
+	/* Possibly updates dsp if the node is active on the device and there
+	 * is dsp context. If dsp context is not created yet,
+	 * cras_iodev_update_dsp returns right away. */
+	if (iodev->active_node == node)
+		cras_iodev_update_dsp(iodev);
+	return 0;
+}
+
 void cras_iodev_free_format(struct cras_iodev *iodev)
 {
 	free(iodev->format);
diff --git a/cras/src/server/cras_iodev.h b/cras/src/server/cras_iodev.h
index ca480bc8..1d32d732 100644
--- a/cras/src/server/cras_iodev.h
+++ b/cras/src/server/cras_iodev.h
@@ -296,6 +296,22 @@ void cras_iodev_set_capture_timestamp(size_t frame_rate,
  */
 void cras_iodev_update_dsp(struct cras_iodev *iodev);
 
+
+/* Sets swap mode on a node using dsp. This function can be called when
+ * dsp pipline is not created yet. It will take effect when dsp pipeline
+ * is created later. If there is dsp pipeline, this function causes the dsp
+ * pipeline to be reloaded and swap mode takes effect right away.
+ * Args:
+ *    iodev - device to be changed for swap mode.
+ *    node - the node to be changed for swap mode.
+ *    enable - 1 to enable swap mode, 0 otherwise.
+ * Returns:
+ *    0 on success, error code on failure.
+ */
+int cras_iodev_dsp_set_swap_mode_for_node(struct cras_iodev *iodev,
+					   struct cras_ionode *node,
+					   int enable);
+
 /* Handles a plug event happening on this node.
  * Args:
  *    node - ionode on which a plug event was detected.
diff --git a/cras/src/tests/alsa_io_unittest.cc b/cras/src/tests/alsa_io_unittest.cc
index 26daa966..eeec9c1a 100644
--- a/cras/src/tests/alsa_io_unittest.cc
+++ b/cras/src/tests/alsa_io_unittest.cc
@@ -148,6 +148,7 @@ static int cras_alsa_resume_appl_ptr_ahead;
 static int ucm_get_optimize_no_stream_flag_ret;
 static int ucm_get_enable_htimestamp_flag_ret;
 static const struct cras_volume_curve *fake_get_dBFS_volume_curve_val;
+static int cras_iodev_dsp_set_swap_mode_for_node_called;
 
 void ResetStubData() {
   cras_alsa_open_called = 0;
@@ -234,6 +235,7 @@ void ResetStubData() {
   ucm_get_optimize_no_stream_flag_ret = 0;
   ucm_get_enable_htimestamp_flag_ret = 0;
   fake_get_dBFS_volume_curve_val = NULL;
+  cras_iodev_dsp_set_swap_mode_for_node_called = 0;
 }
 
 static long fake_get_dBFS(const struct cras_volume_curve *curve, size_t volume)
@@ -821,7 +823,10 @@ TEST(AlsaIoInit, SwapMode) {
                                             fake_mixer, fake_ucm, fake_hctl,
                                             CRAS_STREAM_OUTPUT, 0, 0);
   ASSERT_EQ(0, alsa_iodev_legacy_complete_init((struct cras_iodev *)aio));
-  EXPECT_EQ(NULL, aio->base.set_swap_mode_for_node);
+
+  aio->base.set_swap_mode_for_node((cras_iodev*)aio, fake_node, 1);
+  /* Swap mode is implemented by dsp. */
+  EXPECT_EQ(1, cras_iodev_dsp_set_swap_mode_for_node_called);
 
   // Stub replies that swap mode exists.
   ucm_swap_mode_exists_ret_value = 1;
@@ -2605,4 +2610,12 @@ enum CRAS_IODEV_STATE cras_iodev_state(const struct cras_iodev *iodev)
   return iodev->state;
 }
 
+int cras_iodev_dsp_set_swap_mode_for_node(struct cras_iodev *iodev,
+                                          struct cras_ionode *node,
+                                          int enable)
+{
+  cras_iodev_dsp_set_swap_mode_for_node_called++;
+  return 0;
+}
+
 }
diff --git a/cras/src/tests/iodev_unittest.cc b/cras/src/tests/iodev_unittest.cc
index c59627e1..6a71413a 100644
--- a/cras/src/tests/iodev_unittest.cc
+++ b/cras/src/tests/iodev_unittest.cc
@@ -1433,6 +1433,12 @@ void cras_dsp_set_variable_string(struct cras_dsp_context *ctx, const char *key,
 {
 }
 
+void cras_dsp_set_variable_boolean(struct cras_dsp_context *ctx,
+                                   const char *key,
+                                   char value)
+{
+}
+
 struct pipeline *cras_dsp_get_pipeline(struct cras_dsp_context *ctx)
 {
   cras_dsp_get_pipeline_called++;