test/kms_plane_alpha_blend: clearer validation for coverage-7efc

Inspired by previous change in alpha-7efc[1], get a clearer validation
for the swappable property of plane_alpha and fg.alpha in the coverage
blend formula. Get rid of the 8-increment alpha loop by refactoring
coverage-7efc to a one-shot assert format, avoiding doubts related to
bit precision and rounding issue.

[1] Commit f9efaee9565f ("tests/kms_plane_alpha_blend: refactor
alpha-7efc for clearer validation")

v2:
- add commit reference to alpha-7efc change

Signed-off-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Sung Joon Kim <sungkim@amd.com>

1 files changed, 11 insertions, 13 deletions

diff --git a/tests/kms_plane_alpha_blend.c b/tests/kms_plane_alpha_blend.c
index 8e54dfd6..bd064d1e 100644
--- a/tests/kms_plane_alpha_blend.c
+++ b/tests/kms_plane_alpha_blend.c
@@ -413,27 +413,24 @@ static void coverage_7efc(data_t *data, enum pipe pipe, igt_plane_t *plane)
 {
 	igt_display_t *display = &data->display;
 	igt_crc_t ref_crc = {}, crc = {};
-	int i;
 
 	igt_require(igt_plane_try_prop_enum(plane, IGT_PLANE_PIXEL_BLEND_MODE, "Coverage"));
 	igt_display_commit2(display, COMMIT_ATOMIC);
 	igt_pipe_crc_start(data->pipe_crc);
 
 	/* for coverage, plane alpha and fb alpha should be swappable, so swap fb and alpha */
-	for (i = 0; i < 256; i += 8) {
-		igt_plane_set_prop_value(plane, IGT_PLANE_ALPHA, ((i/2) << 8) | (i/2));
-		igt_plane_set_fb(plane, &data->argb_fb_cov_fc);
-		igt_display_commit2(display, COMMIT_ATOMIC);
+	igt_plane_set_prop_value(plane, IGT_PLANE_ALPHA, 0x7e7e);
+	igt_plane_set_fb(plane, &data->argb_fb_cov_fc);
+	igt_display_commit2(display, COMMIT_ATOMIC);
 
-		igt_pipe_crc_get_current(display->drm_fd, data->pipe_crc, &ref_crc);
+	igt_pipe_crc_get_current(display->drm_fd, data->pipe_crc, &ref_crc);
 
-		igt_plane_set_prop_value(plane, IGT_PLANE_ALPHA, (i << 8) | i);
-		igt_plane_set_fb(plane, &data->argb_fb_cov_7e);
-		igt_display_commit2(display, COMMIT_ATOMIC);
+	igt_plane_set_prop_value(plane, IGT_PLANE_ALPHA, 0xfcfc);
+	igt_plane_set_fb(plane, &data->argb_fb_cov_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);
-	}
+	igt_pipe_crc_get_current(display->drm_fd, data->pipe_crc, &crc);
+	igt_assert_crc_equal(&ref_crc, &crc);
 
 	igt_pipe_crc_stop(data->pipe_crc);
 }
@@ -537,7 +534,8 @@ static void run_subtests(data_t *data, enum pipe pipe)
 	igt_subtest_f("pipe-%s-alpha-7efc", kmstest_pipe_name(pipe))
 		run_test_on_pipe_planes(data, pipe, false, true, alpha_7efc);
 
-	igt_describe("Tests pipe coverage blending properties.");
+	igt_describe("Uses alpha values 0x7e and 0xfc to validate fg.alpha and "
+		     "plane_alpha are swappable on coverage blend mode.");
 	igt_subtest_f("pipe-%s-coverage-7efc", kmstest_pipe_name(pipe))
 		run_test_on_pipe_planes(data, pipe, true, true, coverage_7efc);