tests/kms_plane_alpha_blend: Skip coverage-vs-premult-vs-none for 6bpc panels

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@intel.com>
Credits-to: Juha-pekka Heikkila <juha-pekka.heikkila@intel.com>
Credits-to: Modem Bhanuprakash <Bhanuprakash.Modem@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/tests/kms_plane_alpha_blend.c b/tests/kms_plane_alpha_blend.c
index a37cb27c..a3529dc2 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_f(!is_6bpc(display, pipe), "Test skipped for 6bpc panels\n");
+
 	igt_pipe_crc_start(data->pipe_crc);
 	igt_pipe_crc_get_single(data->pipe_crc, &ref_crc);