Re: [PATCH i-g-t 1/2] lib/igt_kms: Make helper use out-parameter

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

On Mon, 23 Mar 2026, Pranay Samala <pranay.samala@intel.com> wrote:
> Convert igt_get_non_joiner_mode() helper from returning a mode
> pointer to returning bool and filling an output parameter.
>
> Returning connector-owned pointer becomes invalid after connecter
> state changes/resets. Hence copying into called-owned argument,
> which keeps data stable and safe.
> Also update the doc for the new argument and return semantics.

This breaks the build and thus bisect.

Please do something like

$ git rebase -i origin -x 'ninja -C build'

before sending to ensure every commit builds.

BR,
Jani.

>
> Fixes: e404926ca0d7 ("lib/igt_kms: Add helper to get non-joiner mode")
> Signed-off-by: Pranay Samala <pranay.samala@intel.com>
> ---
>  lib/igt_kms.c | 10 ++++++----
>  lib/igt_kms.h |  2 +-
>  2 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index 197ed15d1..118890014 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -7057,13 +7057,14 @@ bool ultrajoiner_mode_found(int drm_fd, drmModeConnector *connector,
>   * igt_get_non_joiner_mode:
>   * @drm_fd: drm file descriptor
>   * @output: pointer to the output structure
> + * @mode: a pointer to a drm mode structure
>   *
>   * Finds the display mode from the output that does not require
>   * Big Joiner or Ultra Joiner.
>   *
> - * Returns: Pointer to non-joiner mode, or NULL if not found.
> + * Returns: True if non-joiner mode found.
>   */
> -drmModeModeInfo *igt_get_non_joiner_mode(int drm_fd, igt_output_t *output)
> +bool igt_get_non_joiner_mode(int drm_fd, igt_output_t *output, drmModeModeInfo *mode)
>  {
>  	drmModeConnector *connector;
>  	int max_dotclock;
> @@ -7077,11 +7078,12 @@ drmModeModeInfo *igt_get_non_joiner_mode(int drm_fd, igt_output_t *output)
>  		/* Check if mode requires joiner */
>  		if (!igt_bigjoiner_possible(drm_fd, current_mode, max_dotclock) &&
>  		    !igt_ultrajoiner_possible(drm_fd, current_mode, max_dotclock)) {
> -			return current_mode;
> +			*mode = *current_mode;
> +			return true;
>  		}
>  	}
>  
> -	return NULL;
> +	return false;
>  }
>  
>  /**
> diff --git a/lib/igt_kms.h b/lib/igt_kms.h
> index 71ed4604e..d63836588 100644
> --- a/lib/igt_kms.h
> +++ b/lib/igt_kms.h
> @@ -1259,7 +1259,7 @@ bool igt_ultrajoiner_possible(int drmfd, drmModeModeInfo *mode, int max_dotclock
>  bool ultrajoiner_mode_found(int drm_fd, drmModeConnector *connector,
>  			  int max_dotclock, drmModeModeInfo *mode);
>  bool igt_has_force_joiner_debugfs(int drmfd, char *conn_name);
> -drmModeModeInfo *igt_get_non_joiner_mode(int drm_fd, igt_output_t *output);
> +bool igt_get_non_joiner_mode(int drm_fd, igt_output_t *output, drmModeModeInfo *mode);
>  bool is_joiner_mode(int drm_fd, igt_output_t *output);
>  bool igt_check_force_joiner_status(int drmfd, char *connector_name);
>  bool igt_check_bigjoiner_support(igt_display_t *display);

-- 
Jani Nikula, Intel