[igt-dev] [PATCH i-g-t] tests/kms_plane_alpha_blend: Dont commit primary for 6bpc display in coverage-vs-premult-vs-none

[Srinivas, Vidya]

Hello,

We checked that the same test works on a different Jasperlake system which has 8bpc. Our device has 6bpc panel and dithering is ON.
Can we use this patch as solution? If any one has a 6bpc panel, can you kindly let us know if its working for you? Thank you so much.

The same test works on HDMI connected to the system, just fails on the eDP which is 6bpc.

https://patchwork.freedesktop.org/patch/442435/?series=90828&rev=8

Regards
Vidya

-----Original Message-----
From: Srinivas, Vidya <vidya.srinivas at intel.com> 
Sent: Saturday, July 3, 2021 9:23 PM
To: igt-dev at lists.freedesktop.org
Cc: Srinivas, Vidya <vidya.srinivas at intel.com>
Subject: [PATCH i-g-t] tests/kms_plane_alpha_blend: Dont commit primary for 6bpc display in coverage-vs-premult-vs-none

Intel Gen11 6bpc panels are giving CRC mismatch in coverage-vs-premult-vs-none if primary gray fb is commited before starting alpha tests. Patch removes primar plane commit if device is intel and 6bpc.

Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
---
 tests/kms_plane_alpha_blend.c | 36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/tests/kms_plane_alpha_blend.c b/tests/kms_plane_alpha_blend.c index a37cb27c7d62..5f0a8cb070dd 100644
--- a/tests/kms_plane_alpha_blend.c
+++ b/tests/kms_plane_alpha_blend.c
@@ -25,6 +25,7 @@
  */
 
 #include "igt.h"
+#include <string.h>
 
 IGT_TEST_DESCRIPTION("Test plane alpha and blending mode properties");
 
@@ -442,14 +443,45 @@ 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) {
+	char buf[4096];
+	char *str;
+	bool ret;
+	int debugfs_fd;
+
+	if (!is_i915_device(display->drm_fd))
+		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 (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;
 	igt_crc_t ref_crc = {}, crc = {};
 
+
 	/* Set a background color on the primary fb for testing */
-	if (plane->type != DRM_PLANE_TYPE_PRIMARY)
-		igt_plane_set_fb(igt_pipe_get_plane_type(&display->pipes[pipe], DRM_PLANE_TYPE_PRIMARY), &data->gray_fb);
+	if (plane->type != DRM_PLANE_TYPE_PRIMARY) {
+		if (!is_6bpc(display))
+			igt_plane_set_fb(igt_pipe_get_plane_type(&display->pipes[pipe],
+						DRM_PLANE_TYPE_PRIMARY), &data->gray_fb);
+	}
 
 	igt_plane_set_prop_enum(plane, IGT_PLANE_PIXEL_BLEND_MODE, "Coverage");
 	igt_plane_set_fb(plane, &data->argb_fb_cov_7e);
--
2.7.4