Re: [i-g-t,v2 1/2] tests/amdgpu/amd_dp_dsc: Do not disable DSC for high bw panels

[Alex Hung <alex.hung@amd.com>]

Reviewed-by: Alex Hung <alex.hung@amd.com>

On 9/3/26 13:24, George Zhang wrote:
> The test previously attempted to disable DSC even on high bandwidth
> panels. This would erroneously fail the dsc_enable test even though DSC
> is on.
> 
> Fix this by checking what mode the panel defaults to when set to
> automatic. If DSC is on, then do not attempt to force it off later.
> 
> Signed-off-by: George Zhang <george.zhang@amd.com>
> ---
>   tests/amdgpu/amd_dp_dsc.c | 20 ++++++++++++++++----
>   1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/amdgpu/amd_dp_dsc.c b/tests/amdgpu/amd_dp_dsc.c
> index dc71e903e..690a6c39d 100644
> --- a/tests/amdgpu/amd_dp_dsc.c
> +++ b/tests/amdgpu/amd_dp_dsc.c
> @@ -137,6 +137,9 @@ static void test_dsc_enable(data_t *data)
>   		igt_output_set_crtc(output,
>   				    crtc);
>   		igt_plane_set_fb(data->primary[crtc->crtc_index], &ref_fb);
> +
> +		/* Make sure we are in automatic mode before we start */
> +		igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_AUTOMATIC);
>   		igt_display_commit_atomic(display, DRM_MODE_ATOMIC_ALLOW_MODESET, 0);
>   
>   		test_conn_cnt++;
> @@ -153,8 +156,12 @@ static void test_dsc_enable(data_t *data)
>   		/* Check if DSC is enabled */
>   		dsc_on = igt_amd_read_dsc_clock_status(data->fd, output->name) == 1;
>   
> -		/* Revert DSC to automatic state */
> -		igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_FORCE_OFF);
> +		/**
> +		 * We can only force off if the panel is capable of running with DSC disabled.
> +		 * If DSC was ON in automatic mode, we cannot (and should not) force it OFF.
> +		 */
> +		if (!dsc_before)
> +			igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_FORCE_OFF);
>   
>   		igt_plane_set_fb(data->primary[crtc->crtc_index], &ref_fb);
>   		igt_display_commit_atomic(display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
> @@ -286,6 +293,7 @@ static void test_dsc_slice_dimensions_change(data_t *data)
>   		igt_output_set_crtc(output,
>   				    crtc);
>   		igt_plane_set_fb(data->primary[crtc->crtc_index], &ref_fb);
> +		igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_AUTOMATIC);
>   		igt_display_commit_atomic(display, DRM_MODE_ATOMIC_ALLOW_MODESET, 0);
>   
>   		test_conn_cnt++;
> @@ -316,8 +324,12 @@ static void test_dsc_slice_dimensions_change(data_t *data)
>   							     ref_fb);
>   		}
>   
> -		/* Force disable DSC */
> -		igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_FORCE_OFF);
> +		/**
> +		 * We can only force off if the panel is capable of running with DSC disabled.
> +		 * If DSC was ON in automatic mode, we cannot (and should not) force it OFF.
> +		 */
> +		if (!dsc_before)
> +			igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_FORCE_OFF);
>   
>   		igt_plane_set_fb(data->primary[crtc->crtc_index], &ref_fb);
>   		igt_display_commit_atomic(display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);