[PATCH i-g-t] tests/intel/kms_cdclk: Skip mode-transition subtest on eDP outputs with fixed modes

[Shankar, Uma]

> -----Original Message-----
> From: igt-dev <igt-dev-bounces at lists.freedesktop.org> On Behalf Of Swati
> Sharma
> Sent: Friday, May 23, 2025 2:47 PM
> To: igt-dev at lists.freedesktop.org
> Cc: Sharma, Swati2 <swati2.sharma at intel.com>
> Subject: [PATCH i-g-t] tests/intel/kms_cdclk: Skip mode-transition subtest on eDP
> outputs with fixed modes
> 
> eDP panels typically advertise a limited set of fixed modes, often with minimal
> variation (e.g., only differing in refresh rate). As a result, the computed CDCLK
> frequency for both high and low refresh rate modes can be identical, preventing a
> CDCLK bump and causing the test to fail unnecessarily.
> 
> To avoid such false negatives, skip the CDCLK bump test on eDP outputs and
> restrict testing to external outputs like DP and HDMI, where a wider range of
> modes is available and CDCLK bumps can be meaningfully validated.

I think its ok to drop eDP but we may have HDMI/DP panels as well where difference in
pixel clocks supported based on the modes may still be less to trigger meaningful CD clock
changes. Example can be a FHD HDMI or DP monitor, so lets enhance this check and
introduce a minimum pixel clock delta as a IGT_REQUIRE condition.

Regards,
Uma Shankar

> Signed-off-by: Swati Sharma <swati2.sharma at intel.com>
> ---
>  tests/intel/kms_cdclk.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/tests/intel/kms_cdclk.c b/tests/intel/kms_cdclk.c index
> 0c7c235f3..4c6dd9276 100644
> --- a/tests/intel/kms_cdclk.c
> +++ b/tests/intel/kms_cdclk.c
> @@ -325,6 +325,13 @@ static void run_cdclk_test(data_t *data, uint32_t flags)
>  	enum pipe pipe;
> 
>  	for_each_pipe_with_valid_output(display, pipe, output) {
> +		drmModeConnectorPtr c = output->config.connector;
> +
> +		/* Skip eDP outputs as they typically have fixed
> +		 * modes and won't trigger CDCLK bump. */
> +		if (c->connector_type == DRM_MODE_CONNECTOR_eDP)
> +			continue;
> +
>  		igt_output_set_pipe(output, pipe);
>  		if (!intel_pipe_output_combo_valid(display)) {
>  			igt_output_set_pipe(output, PIPE_NONE);
> --
> 2.25.1