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

[Pranay Samala <pranay.samala@intel.com>]

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.

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);
-- 
2.34.1