[igt-dev] [PATCH i-g-t] tests/kms_plane_alpha_blend: Skip coverage-vs-premult-vs-none for 6bpc panels

[Vidya Srinivas]

Intel platforms using 6bpc panels have dithering ON
and show CRC mismatch in coverage-vs-premult-vs-none
Doing a crc based test with dithering is not a great idea as pixels
will change due to the 8bit to 6bits truncation with dithering.

This patch skips the subtest for 6bpc panels. Currently, there is no better
way of fetching the bpc info other than EDID or display_info. Currently using
i915_display_info for the same. Hence restricting the check to i915 devices only.

Credits-to: Uma Shankar <uma.shankar at intel.com>
Credits-to: Juha-pekka Heikkila <juha-pekka.heikkila at intel.com>
Credits-to: Modem Bhanuprakash <Bhanuprakash.Modem at intel.com>
Reviewed-by: Uma Shankar <uma.shankar at intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
---
 tests/kms_plane_alpha_blend.c | 36 +++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/tests/kms_plane_alpha_blend.c b/tests/kms_plane_alpha_blend.c
index a37cb27c7d62..eb45dcc16a6d 100644
--- a/tests/kms_plane_alpha_blend.c
+++ b/tests/kms_plane_alpha_blend.c
@@ -442,6 +442,38 @@ static void coverage_7efc(data_t *data, enum pipe pipe, igt_plane_t *plane)
 	igt_pipe_crc_stop(data->pipe_crc);
 }
 
+static bool is_6bpc(igt_display_t *display, enum pipe pipe) {
+	char buf[8192];
+	char *str;
+	bool ret;
+	int debugfs_fd;
+	drmModeConnector *c;
+	igt_output_t *output = igt_get_single_output_for_pipe(display, pipe);
+
+	if (!is_i915_device(display->drm_fd))
+		return false;
+
+	c = output->config.connector;
+	if (c->connector_type != DRM_MODE_CONNECTOR_eDP ||
+		c->connector_type != DRM_MODE_CONNECTOR_DSI)
+		return false;
+
+	debugfs_fd = igt_debugfs_dir(display->drm_fd);
+	if (debugfs_fd < 0)
+		return false;
+
+	igt_debugfs_simple_read(debugfs_fd, "i915_display_info", buf, sizeof(buf));
+
+	str = strstr(buf, "bpp=");
+	if (str && (strncmp(str, "bpp=18", 6) == 0))
+		ret = true;
+	else
+		ret = false;
+
+	close(debugfs_fd);
+	return ret;
+}
+
 static void coverage_premult_constant(data_t *data, enum pipe pipe, igt_plane_t *plane)
 {
 	igt_display_t *display = &data->display;
@@ -454,6 +486,10 @@ static void coverage_premult_constant(data_t *data, enum pipe pipe, igt_plane_t
 	igt_plane_set_prop_enum(plane, IGT_PLANE_PIXEL_BLEND_MODE, "Coverage");
 	igt_plane_set_fb(plane, &data->argb_fb_cov_7e);
 	igt_display_commit2(display, COMMIT_ATOMIC);
+
+	/* 6bpc panels have dithering ON and CRC might fail, hence skip test */
+	igt_require(is_6bpc(display, pipe) == false);
+
 	igt_pipe_crc_start(data->pipe_crc);
 	igt_pipe_crc_get_single(data->pipe_crc, &ref_crc);
 
-- 
2.32.0