Re: [PATCH i-g-t 2/3] lib/igt_kms: Fix max_non_joiner_mode_found

["Thasleem, Mohammed" <mohammed.thasleem@intel.com>]

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On 20-02-2026 08:52 pm, Kunal Joshi wrote:
> The function previously required hdisplay == max_pipe_hdisplay (5120 on
> pre-Gen30), which means it returned false for any connector whose maximum
> resolution is below the pipe limit (e.g. a 4K MST output on a 5K-capable
> platform).
>
> Fix this by iterating all modes and tracking the best one (highest
> hdisplay, then highest clock as a tiebreaker) that does not require a
> big joiner, as determined by igt_bigjoiner_possible(). This correctly
> handles connectors with any max resolution.
>
> Fixes: 3830ca6a5068 ("lib/igt_kms: Add support to check joiner mode limit")
> Signed-off-by: Kunal Joshi<kunal1.joshi@intel.com>

  LGTM:

Reviewed-by: Mohammed Thasleem <mohammed.thasleem@intel.com>


> ---
>   lib/igt_kms.c | 15 ++++++++++-----
>   1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index 5c4879604..c6678b02b 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -6904,19 +6904,24 @@ bool bigjoiner_mode_found(int drm_fd, drmModeConnector *connector,
>   bool max_non_joiner_mode_found(int drm_fd, drmModeConnector *connector,
>   			   int max_dotclock, drmModeModeInfo *mode)
>   {
> -	int max_hdisplay = get_max_pipe_hdisplay(drm_fd);
> +	bool found = false;
>   
>   	for (int i = 0; i < connector->count_modes; i++) {
>   		drmModeModeInfo *current_mode = &connector->modes[i];
>   
> -		if (current_mode->hdisplay == max_hdisplay &&
> -		    current_mode->clock < max_dotclock) {
> +		if (igt_bigjoiner_possible(drm_fd, current_mode, max_dotclock))
> +			continue;
> +
> +		if (!found ||
> +		    current_mode->hdisplay > mode->hdisplay ||
> +		    (current_mode->hdisplay == mode->hdisplay &&
> +		     current_mode->clock > mode->clock)) {
>   			*mode = *current_mode;
> -			return true;
> +			found = true;
>   		}
>   	}
>   
> -	return false;
> +	return found;
>   }
>   
>   /* TODO: Move these lib functions to the joiner-specific library file

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