[PATCH i-g-t v2 1/1] tests/kms_color: Add 10-bit color depth support to gamma test for MediaTek

Jay Liu
2026-04-13T01:42:00Z

1. Add 10-bit color depth flow to gamma test for MediaTek devices, which only
support bit-true results with 10-bit data. The test now selects 8-bit or
10-bit color depth and framebuffer format based on device type.

2. To satisfy the legacy gamma test requirements, the MTK Gamma LUT limit
should be set to 4092, in the current 16-bit LUT design, setting the entry
to 0xffd0 ensures the driver maps it correctly to 4092.

Signed-off-by: Jay Liu <jay.liu@mediatek.com>
---
tests/kms_color.c | 35 +++++++++++++++++++++++++++--------
1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/tests/kms_color.c b/tests/kms_color.c
index 565edb2dc..033207368 100644
--- a/tests/kms_color.c
+++ b/tests/kms_color.c
@@ -288,7 +288,7 @@ static bool test_pipe_legacy_gamma(data_t *data,
fb_id = igt_create_fb(data->drm_fd,
mode->hdisplay,
mode->vdisplay,
- DRM_FORMAT_XRGB8888,
+ data->drm_format,
DRM_FORMAT_MOD_LINEAR,
&fb);
igt_assert(fb_id);
@@ -296,7 +296,7 @@ static bool test_pipe_legacy_gamma(data_t *data,
fb_modeset_id = igt_create_fb(data->drm_fd,
mode->hdisplay,
mode->vdisplay,
- DRM_FORMAT_XRGB8888,
+ data->drm_format,
DRM_FORMAT_MOD_LINEAR,
&fb_modeset);
igt_assert(fb_modeset_id);
@@ -322,9 +322,20 @@ static bool test_pipe_legacy_gamma(data_t *data,
igt_plane_set_fb(primary, &fb);

red_lut[0] = green_lut[0] = blue_lut[0] = 0;
- for (i = 1; i < legacy_lut_size; i++)
- red_lut[i] = green_lut[i] = blue_lut[i] = 0xffff;
- igt_assert_eq(drmModeCrtcSetGamma(data->drm_fd, primary->crtc->crtc_id,
+ for (i = 1; i < legacy_lut_size; i++) {
+ /*
+ * The Medaitek Gamma LUT maps 10bit input data to 12bit output.
+ * In this test case, the maximum input value is 1023.
+ * When the Gamma function is disabled, the data defaults to a 4092 output.
+ * To achieve bit true results, the Gamma LUT maximum must be set to 4092.
+ * Note that 0xFFFD0 represents 16-bit,which maps to 4092 in 12-bit depth.
+ */
+ if (is_mtk_device(data->drm_fd))
+ red_lut[i] = green_lut[i] = blue_lut[i] = 0xffd0;
+ else
+ red_lut[i] = green_lut[i] = blue_lut[i] = 0xffff;
+ }
+ igt_assert_eq(drmModeCrtcSetGamma(data->drm_fd, primary->pipe->crtc_id,
legacy_lut_size, red_lut, green_lut, blue_lut), 0);
igt_display_commit(&data->display);
igt_wait_for_vblank(primary->crtc);
@@ -752,14 +763,22 @@ static void
run_gamma_degamma_tests_for_crtc(data_t *data, igt_crtc_t *crtc,
bool (*test_t)(data_t*, igt_plane_t*))
{
+ bool is_mtk = false;
+
test_setup(data, crtc);

+ /* MediaTek requires 10-bit pipeline for accurate (bit true) color processing */
+ if (is_mtk_device(data->drm_fd))
+ is_mtk = true;
+
/*
- * We assume an 8bits depth per color for degamma/gamma LUTs
+ * We assume an 8bits or 10bits depth per color for degamma/gamma LUTs
* for CRC checks with framebuffer references.
*/
- data->color_depth = 8;
- data->drm_format = DRM_FORMAT_XRGB8888;
+
+ /* MediaTek requires 10-bit pipeline for accurate (bit true) color processing */
+ data->color_depth = is_mtk ? 10 : 8;
+ data->drm_format = is_mtk ? DRM_FORMAT_XRGB2101010 : DRM_FORMAT_XRGB8888;
data->mode = igt_output_get_mode(data->output);

igt_require(crtc_output_combo_valid(data, crtc));
--
2.46.0