Re: [PATCH i-g-t] tests/kms_setmode: Add HDMI 2.0 clock limit for mode selection

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 1/30/2026 11:24 AM, Jeevan B wrote:
> eDP modes with high clock rates were being forced on HDMI 2.0 displays,
> causing kernel to reject with EINVAL. Add clock validation to skip
> incompatible eDP modes and fall back to supported modes.
>
> Signed-off-by: Jeevan B <jeevan.b@intel.com>
> ---
>   tests/kms_setmode.c | 24 ++++++++++++++++++++++--
>   1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c
> index 9c0649e17..4b2f16751 100644
> --- a/tests/kms_setmode.c
> +++ b/tests/kms_setmode.c
> @@ -79,6 +79,9 @@
>   /* restricted pipe count */
>   #define CRTC_RESTRICT_CNT 2
>   
> +/* Clock limit for HDMI 2.0 */
> +#define HDMI_2_0_MAX_CLOCK_KHZ 600000
> +
>   static int drm_fd;
>   static drmModeRes *drm_resources;
>   static int filter_test_id;
> @@ -270,8 +273,25 @@ static void get_mode_for_crtc(struct crtc_config *crtc,
>   				if (conn->modes[j].clock < mode->clock)
>   					mode = &conn->modes[j];
>   			}
> -			*mode_ret = *mode;
> -			return;
> +
> +			/* Check clock limit for HDMI 2.0 */
> +			bool hdmi_compatible = true;
> +
> +			for (int k = 0; k < crtc->connector_count; k++) {
> +				drmModeConnector *other_conn = crtc->cconfs[k].connector;
> +
> +				if ((other_conn->connector_type == DRM_MODE_CONNECTOR_HDMIA ||
> +				    other_conn->connector_type == DRM_MODE_CONNECTOR_HDMIB) &&
> +				    mode->clock > HDMI_2_0_MAX_CLOCK_KHZ) {

Hmm perhaps can use a helper : hdmi_connector_exceeds_hdmi20_limit()

static bool hdmi_connector_mode_exceeds_hdmi20_limit(drmModeConnector 
*connector,
                              drmModeModeInfo *mode)
{
     if (connector->connector_type != DRM_MODE_CONNECTOR_HDMIA &&
         connector->connector_type != DRM_MODE_CONNECTOR_HDMIB)
         return false;

     return mode->clock > HDMI_2_0_MAX_CLOCK_KHZ;
}

> +					hdmi_compatible = false;
> +					break;
> +				}
> +			}
> +
> +			if (hdmi_compatible && crtc_supports_mode(crtc, mode)) {

Need to drop crtc_supports_mode(crtc, mode) here, otherwise it will try 
to match this mode.

This will prevent the test to use eDP modes that might not be enumerated 
in external panels but can still be supported.


Regards,

Ankit


> +				*mode_ret = *mode;
> +				return;
> +			}
>   		}
>   	}
>