[PATCH i-g-t] tests/km_pm_brightness.c: check for flickers while adjusting the brightness.

[Santhosh Reddy Guddati]

The test is added to check for flickers on the panel while
changing brightness.Though changing the brightness doesn't have impact
on CRC,but if there is a flicker observed , the crc will change
and this test validates the crc.
---
 tests/intel/kms_pm_backlight.c | 44 ++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/tests/intel/kms_pm_backlight.c b/tests/intel/kms_pm_backlight.c
index 8672afa7a..e29fd7320 100644
--- a/tests/intel/kms_pm_backlight.c
+++ b/tests/intel/kms_pm_backlight.c
@@ -64,6 +64,10 @@
  * SUBTEST: fade-with-suspend
  * Description: Test the fade with suspend.
  * Functionality: backlight, suspend
+ *
+ * SUBTEST: brightness-crc-change
+ * Description: Test the brightness change with CRC.
+ * Functionality: backlight, CRC
  */
 
 struct context {
@@ -255,6 +259,44 @@ static void test_setup(igt_display_t display, igt_output_t *output)
 	}
 }
 
+static void test_brightness_crc(struct context *context)
+{
+	int min = 0;
+	int max = context->max;
+	int step = (max - min) / 10;
+	int brightness;
+	igt_crc_t out_crc_before, out_crc_after;
+	igt_display_t *display = context->output->display;
+	char *crc_str;
+	igt_pipe_crc_t *ref_crc;
+
+	// Get the CRC before changing brightness
+	ref_crc = igt_pipe_crc_new(display->drm_fd, context->output->config.pipe, IGT_PIPE_CRC_SOURCE_AUTO);
+	igt_assert(ref_crc);
+
+	for (brightness = min; brightness <= max; brightness += step) {
+		igt_info("Brightness: %d\n", brightness);
+
+		igt_pipe_crc_collect_crc(ref_crc, &out_crc_before);
+		crc_str = igt_crc_to_string(&out_crc_before);
+		igt_debug("CRC before write: %s\n", crc_str);
+
+		igt_assert_eq(backlight_write(brightness, "brightness", context), 0);
+		igt_debug("Brightness after write: %d\n", brightness);
+
+		igt_pipe_crc_collect_crc(ref_crc, &out_crc_after);
+		crc_str = igt_crc_to_string(&out_crc_after);
+		igt_debug("CRC after write: %s\n", crc_str);
+
+		// Compare the CRC values
+		if (igt_check_crc_equal(&out_crc_before, &out_crc_after)) {
+			igt_info("CRC values are same for brightness: %d\n", brightness);
+		} else {
+			igt_info("CRC values are different for brightness: %d\n", brightness);
+		}
+	}
+}
+
 igt_main
 {
 	int fd;
@@ -275,6 +317,7 @@ igt_main
 		{ "fade", "test basic fade.", test_fade, TEST_NONE },
 		{ "fade-with-dpms", "test the fade with DPMS.", test_fade, TEST_DPMS },
 		{ "fade-with-suspend", "test the fade with suspend.", test_fade, TEST_SUSPEND },
+		{ "brightness-crc-change", "test the brightness change with CRC.", test_brightness_crc, TEST_NONE },
 	};
 
 	igt_fixture {
@@ -288,6 +331,7 @@ igt_main
 		 */
 		kmstest_set_vt_graphics_mode();
 		igt_display_require(&display, drm_open_driver(DRIVER_INTEL | DRIVER_XE));
+		igt_require_pipe_crc(display.drm_fd);
 
 		for_each_connected_output(&display, output) {
 			if (output->config.connector->connector_type != DRM_MODE_CONNECTOR_eDP)
-- 
2.34.1