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

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

On 9/2/26 09:57, 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.

Doesn't high bandwidth panel need DSC off? How is a high bandwidth panel 
expected to behave?

> 
> Signed-off-by: George Zhang <george.zhang@amd.com>
> ---
>   tests/amdgpu/amd_dp_dsc.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/amdgpu/amd_dp_dsc.c b/tests/amdgpu/amd_dp_dsc.c
> index dc71e903e..ccaf64c66 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*/
Add a space after start, i.e., "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++;
> @@ -154,7 +157,9 @@ static void test_dsc_enable(data_t *data)
>   		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);
> +		if (!dsc_before)
> +			/* We can only force off if the panel allows it. If DSC was on in automatic mode, we cannot force it off. */
Break this one-line comment to multiple lines, and place it before "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 +291,7 @@ 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++;
> @@ -317,7 +323,8 @@ static void test_dsc_slice_dimensions_change(data_t *data)
>   		}
> 
>   		/* Force disable DSC */
Please update this comment too.

> -		igt_amd_write_dsc_clock_en(data->fd, output->name, DSC_FORCE_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);
> --
> 2.55.0