Re: [PATCH i-g-t 1/2] test/kms_color: Clamp CTM values to -2.0~2.0 for MediaTek devices

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jan 28, 2026 at 04:24:42PM +0800, Jason-JH Lin wrote:
> Use clamp to restrict CTM matrix values to the -2.0 to 2.0 range for
> MediaTek devices, ensuring tests do not exceed hardware limits.
> 
> Signed-off-by: Jason-JH Lin <jason-jh.lin@mediatek.com>
> ---
>  tests/kms_color.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/kms_color.c b/tests/kms_color.c
> index b2ca6975d6a5..c6cd35d74a2f 100644
> --- a/tests/kms_color.c
> +++ b/tests/kms_color.c
> @@ -76,6 +76,8 @@
>   * @gamma-lut:          Gamma LUT
>   */
>  
> +#define CTM_SIZE		(9)
> +
>  IGT_TEST_DESCRIPTION("Test Color Features at Pipe level");
>  
>  static bool test_pipe_degamma(data_t *data,
> @@ -1025,7 +1027,7 @@ run_tests_for_pipe(data_t *data)
>  		const char *name;
>  		int iter;
>  		const color_t *fb_colors;
> -		double ctm[9];
> +		double ctm[CTM_SIZE];
>  		const char *desc;
>  	} ctm_tests[] = {
>  		{ .name = "ctm-red-to-blue",
> @@ -1128,6 +1130,19 @@ run_tests_for_pipe(data_t *data)
>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(ctm_tests); i++) {
> +		double fixed_ctm[CTM_SIZE];
> +		const double *ctm_ptr = ctm_tests[i].ctm;
> +
> +		/* The valid value of MediaTek color matrix range is -2.0 ~ 2.0 */
> +		if (is_mtk_device(data->drm_fd)) {
> +			int j;
> +
> +			for (j = 0; j < CTM_SIZE; j++)
> +				fixed_ctm[j] = clamp(ctm_tests[i].ctm[j], -2.0, 2.0);
> +
> +			ctm_ptr = fixed_ctm;
> +		}

The kernel is supposed to clamp this.

> +
>  		igt_describe_f("%s", ctm_tests[i].desc);
>  		igt_subtest_with_dynamic_f("%s", ctm_tests[i].name) {
>  			for_each_pipe_with_valid_output(&data->display, pipe, data->output) {
> @@ -1135,7 +1150,7 @@ run_tests_for_pipe(data_t *data)
>  					      igt_output_name(data->output))
>  					run_ctm_tests_for_pipe(data, pipe,
>  							       ctm_tests[i].fb_colors,
> -							       ctm_tests[i].ctm,
> +							       ctm_ptr,
>  							       ctm_tests[i].iter);
>  				if (igt_run_in_simulation())
>  					break;
> -- 
> 2.43.0

-- 
Ville Syrjälä
Intel