[PATCH i-g-t 3/6] lib/igt_kms: Fix max_non_joiner_mode_found

[Kunal Joshi <kunal1.joshi@intel.com>]

Previously the function, instead of giving the highest possible mode the
connector could support, started the check by looking if the mode was
equal to max_pipe_hdisplay. There may be corner cases where a connector never supports the highest mode our source can
drive (e.g. a 4K mode 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.

v2: Reword commit message (Suraj)

Fixes: 3830ca6a5068 ("lib/igt_kms: Add support to check joiner mode limit")
Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
Reviewed-by: Mohammed Thasleem <mohammed.thasleem@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
---
 lib/igt_kms.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 04b1f3972..dbd419a9b 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -6979,21 +6979,26 @@ bool bigjoiner_mode_found(int drm_fd, drmModeConnector *connector,
  * false otherwise.
  */
 bool max_non_joiner_mode_found(int drm_fd, drmModeConnector *connector,
-			   int max_dotclock, drmModeModeInfo *mode)
+			       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
-- 
2.48.1