Re: [PATCH i-g-t v2] tests/kms_setmode: Add HDMI 2.0 clock limit for mode selection

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 31 Mar 2026, Jeevan B <jeevan.b@intel.com> 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.
>
> v2: Add HDMI 2.0 clock limit helper, drop crtc_supports_mode(),
>     and ensure per-connector compatibility to avoid invalid modes.
>
> Signed-off-by: Jeevan B <jeevan.b@intel.com>
> ---
>  tests/kms_setmode.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c
> index 1f2849bc2..f1c1afe45 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;
> @@ -165,6 +168,16 @@ static bool connector_supports_mode(drmModeConnector *connector,
>  	return false;
>  }
>  
> +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;
> +}
> +
>  static bool crtc_supports_mode(struct crtc_config *crtc, drmModeModeInfo *mode)
>  {
>  	int i;
> @@ -270,8 +283,35 @@ 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 HDMI 2.0 clock + per-connector compatibility */
> +			{
> +				int k;
> +				bool compatible = true;
> +
> +				for (k = 0; k < crtc->connector_count; k++) {
> +					drmModeConnector *other_conn =
> +						crtc->cconfs[k].connector;
> +
> +					/* HDMI 2.0 clock constraint */
> +					if (hdmi_connector_mode_exceeds_hdmi20_limit(other_conn,
> +										     mode)) {
> +						compatible = false;
> +						break;
> +					}
> +
> +					/* Ensure connector supports the mode */
> +					if (!connector_supports_mode(other_conn, mode)) {
> +						compatible = false;
> +						break;
> +					}
> +				}
> +
> +				if (compatible) {
> +					*mode_ret = *mode;
> +					return;
> +				}
> +			}

Please abstract the whole thing into a function. Having those {} blocks
inline is messy.

BR,
Jani.

>  		}
>  	}

-- 
Jani Nikula, Intel