tests/kms_chamelium: test audio channels are not mixed up

Send a different signal to each channel and make sure captured audio channels
are not swapped or mixed up.

The Chamelium device has a bug and already swaps the left and right channels.
For this reason, clients need to retrieve the Chamelium channel mapping and
accomodate for this. See https://crbug.com/950922 for a discussion about this.

Signed-off-by: Simon Ser <simon.ser@intel.com>
Reviewed-by: Martin Peres <martin.peres@linux.intel.com>

3 files changed, 73 insertions, 8 deletions

diff --git a/lib/igt_chamelium.c b/lib/igt_chamelium.c
index 7c9030d1..6ac7b722 100644
--- a/lib/igt_chamelium.c
+++ b/lib/igt_chamelium.c
@@ -931,6 +931,40 @@ int chamelium_get_captured_frame_count(struct chamelium *chamelium)
 }
 
 /**
+ * chamelium_get_audio_channel_mapping:
+ * @chamelium: the Chamelium instance
+ * @port: the audio port
+ * @mapping: will be filled with the channel mapping
+ *
+ * Obtains the channel mapping for an audio port.
+ *
+ * Audio channels are not guaranteed not to be swapped. Users can use the
+ * channel mapping to match an input channel to a capture channel.
+ *
+ * The mapping contains one element per capture channel. Each element indicates
+ * which input channel the capture channel is mapped to. As a special case, -1
+ * means that the channel isn't mapped.
+ */
+void chamelium_get_audio_channel_mapping(struct chamelium *chamelium,
+					 struct chamelium_port *port,
+					 int mapping[static 8])
+{
+	xmlrpc_value *res, *res_channel;
+	int res_len, i;
+
+	res = chamelium_rpc(chamelium, port, "GetAudioChannelMapping", "(i)",
+			    port->id);
+	res_len = xmlrpc_array_size(&chamelium->env, res);
+	igt_assert(res_len == 8);
+	for (i = 0; i < res_len; i++) {
+		xmlrpc_array_read_item(&chamelium->env, res, i, &res_channel);
+		xmlrpc_read_int(&chamelium->env, res_channel, &mapping[i]);
+		xmlrpc_DECREF(res_channel);
+	}
+	xmlrpc_DECREF(res);
+}
+
+/**
  * chamelium_start_capturing_audio:
  * @chamelium: the Chamelium instance
  * @port: the port to capture audio from (it must support audio)
diff --git a/lib/igt_chamelium.h b/lib/igt_chamelium.h
index 047f8c5d..728d16ea 100644
--- a/lib/igt_chamelium.h
+++ b/lib/igt_chamelium.h
@@ -106,6 +106,9 @@ void chamelium_start_capture(struct chamelium *chamelium,
 void chamelium_stop_capture(struct chamelium *chamelium, int frame_count);
 void chamelium_capture(struct chamelium *chamelium, struct chamelium_port *port,
 		       int x, int y, int w, int h, int frame_count);
+void chamelium_get_audio_channel_mapping(struct chamelium *chamelium,
+					 struct chamelium_port *port,
+					 int mapping[static 8]);
 void chamelium_start_capturing_audio(struct chamelium *chamelium,
 				    struct chamelium_port *port, bool save_to_file);
 struct chamelium_audio_file *chamelium_stop_capturing_audio(struct chamelium *chamelium,
diff --git a/tests/kms_chamelium.c b/tests/kms_chamelium.c
index 687f64c4..1118da86 100644
--- a/tests/kms_chamelium.c
+++ b/tests/kms_chamelium.c
@@ -777,7 +777,7 @@ do_test_display_audio(data_t *data, struct chamelium_port *port,
 		      struct alsa *alsa, int playback_channels,
 		      int playback_rate)
 {
-	int ret, capture_rate, capture_channels, msec, freq;
+	int ret, capture_rate, capture_channels, msec, freq, step;
 	struct chamelium_audio_file *audio_file;
 	struct chamelium_stream *stream;
 	enum chamelium_stream_realtime_mode stream_mode;
@@ -792,16 +792,18 @@ do_test_display_audio(data_t *data, struct chamelium_port *port,
 	int dump_fd = -1;
 	pthread_t thread;
 	struct audio_state state = {};
+	int channel_mapping[8], capture_chan;
 
 	if (!alsa_test_output_configuration(alsa, playback_channels,
 					    playback_rate)) {
-		igt_debug("Skipping test with sample rate %d and %d channels "
-			  "because selected output devices don't support this "
-			  "configuration\n", playback_rate, playback_channels);
+		igt_debug("Skipping test with sample rate %d Hz and %d channels "
+			  "because at least one of the selected output devices "
+			  "doesn't support this configuration\n",
+			  playback_rate, playback_channels);
 		return false;
 	}
 
-	igt_debug("Testing with playback sampling rate %d and %d channels\n",
+	igt_debug("Testing with playback sampling rate %d Hz and %d channels\n",
 		  playback_rate, playback_channels);
 	alsa_configure_output(alsa, playback_channels, playback_rate);
 
@@ -830,9 +832,17 @@ do_test_display_audio(data_t *data, struct chamelium_port *port,
 	signal = audio_signal_init(playback_channels, playback_rate);
 	igt_assert(signal);
 
+	/* We'll choose different frequencies per channel to make sure they are
+	 * independent from each other. To do so, we'll add a different offset
+	 * to the base frequencies for each channel. We need to choose a big
+	 * enough offset so that we're sure to detect mixed up channels. We
+	 * choose an offset of two 2 bins in the final FFT to enforce a clear
+	 * difference.
+	 */
+	step = 2 * capture_rate / CAPTURE_SAMPLES;
 	for (i = 0; i < test_frequencies_count; i++) {
 		for (j = 0; j < playback_channels; j++) {
-			freq = test_frequencies[i];
+			freq = test_frequencies[i] + j * step;
 			audio_signal_add_frequency(signal, freq, j);
 		}
 	}
@@ -847,6 +857,20 @@ do_test_display_audio(data_t *data, struct chamelium_port *port,
 	ret = pthread_create(&thread, NULL, run_audio_thread, alsa);
 	igt_assert(ret == 0);
 
+	chamelium_get_audio_channel_mapping(data->chamelium, port,
+					    channel_mapping);
+	/* Make sure we can capture all channels we send. */
+	for (i = 0; i < playback_channels; i++) {
+		ok = false;
+		for (j = 0; j < capture_channels; j++) {
+			if (channel_mapping[j] == i) {
+				ok = true;
+				break;
+			}
+		}
+		igt_assert(ok);
+	}
+
 	/* Needs to be a multiple of 128, because that's the number of samples
 	 * we get per channel each time we receive an audio page from the
 	 * Chamelium device. */
@@ -886,11 +910,15 @@ do_test_display_audio(data_t *data, struct chamelium_port *port,
 		igt_debug("Detecting audio signal, t=%d msec\n", msec);
 
 		for (j = 0; j < playback_channels; j++) {
-			igt_debug("Processing channel %zu\n", j);
+			capture_chan = channel_mapping[j];
+			igt_assert(capture_chan >= 0);
+			igt_debug("Processing channel %zu (captured as "
+				  "channel %d)\n", j, capture_chan);
 
 			audio_extract_channel_s32_le(channel, channel_len,
 						     buf, buf_len,
-						     capture_channels, j);
+						     capture_channels,
+						     capture_chan);
 
 			if (audio_signal_detect(signal, capture_rate, j,
 						channel, channel_len))