Re: [i-g-t, v2 2/2] tests/amdgpu/amd_dp_dsc: Reset link settings after subtest

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

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

On 9/3/26 13:24, George Zhang wrote:
> Currently, the link settings persist after the link settings subtest,
> and can retain a lowered link rate/lane count going into subsequent subtests.
> 
> Fix it by resetting the link settings on an igt_fixture after running
> the dsc_link_settings subtest. We can do so by setting it to lane count
> and link rate unknown and letting the driver set it to the default values.
> 
> Signed-off-by: George Zhang <george.zhang@amd.com>
> ---
>   tests/amdgpu/amd_dp_dsc.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
> 
> diff --git a/tests/amdgpu/amd_dp_dsc.c b/tests/amdgpu/amd_dp_dsc.c
> index 690a6c39d..6c8e76e00 100644
> --- a/tests/amdgpu/amd_dp_dsc.c
> +++ b/tests/amdgpu/amd_dp_dsc.c
> @@ -356,6 +356,23 @@ static void test_dsc_slice_dimensions_change(data_t *data)
>   	igt_skip_on(test_conn_cnt == 0);
>   }
>   
> +static void reset_link_settings(data_t *data)
> +{
> +	igt_output_t *output;
> +	igt_crtc_t *crtc;
> +
> +	for_each_crtc(&data->display, crtc) {
> +		output = data->output[crtc->crtc_index];
> +		if (!output || !igt_output_is_connected(output) ||
> +			!is_dsc_capable(&data->mode[crtc->crtc_index]))
> +			continue;
> +
> +		igt_amd_write_link_settings(data->fd, output->name,
> +					    LANE_COUNT_UNKNOWN, LINK_RATE_UNKNOWN,
> +					    LINK_TRAINING_DEFAULT);
> +	}
> +}
> +
>   static void test_dsc_link_settings(data_t *data)
>   {
>   	igt_output_t *output;
> @@ -609,6 +626,9 @@ int igt_main() {
>   	igt_subtest("dsc-link-settings")
>   	    test_dsc_link_settings(&data);
>   
> +	igt_fixture()
> +		reset_link_settings(&data);
> +
>   	igt_describe("Tests different bpc settings and logs if DSC is enabled/disabled");
>   	igt_subtest("dsc-bpc")
>   	    test_dsc_bpc(&data);