From: igt-dev <redacted> On Behalf Of Vidya
Srinivas
Sent: Thursday, July 8, 2021 6:16 PM
To: igt-dev@lists.freedesktop.org
Subject: [igt-dev] [PATCH i-g-t] 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 [off-list ref]
Credits-to: Juha-pekka Heikkila [off-list ref]
Credits-to: Modem Bhanuprakash [off-list ref]
Reviewed-by: Uma Shankar <redacted>
Signed-off-by: Vidya Srinivas <redacted>
---
 tests/kms_plane_alpha_blend.c | 39 +++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/tests/kms_plane_alpha_blend.c b/tests/kms_plane_alpha_blend.c
index a37cb27c7d62..6560b37981b6 100644
--- a/tests/kms_plane_alpha_blend.c
+++ b/tests/kms_plane_alpha_blend.c

@@ -442,10 +442,42 @@ 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[4096];

 	/* Set a background color on the primary fb for testing */
 	if (plane->type != DRM_PLANE_TYPE_PRIMARY)

@@ -454,6 +486,11 @@ 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 */
+	is6bpc = is_6bpc(display, pipe);
+	igt_require(is6bpc == false);

+
 	igt_pipe_crc_start(data->pipe_crc);
 	igt_pipe_crc_get_single(data->pipe_crc, &ref_crc);

@@ -461,14 +498,12 @@ static void coverage_premult_constant(data_t *data, enum

pipe pipe, igt_plane_t
 	igt_plane_set_fb(plane, &data->argb_fb_7e);
 	igt_display_commit2(display, COMMIT_ATOMIC);
 	igt_pipe_crc_get_current(display->drm_fd, data->pipe_crc, &crc);
-	igt_assert_crc_equal(&ref_crc, &crc);