drm: mode: Allow NULL modes for equality check

Since we're now using mode == NULL to represent disabled, it's not
wholly surprising that we'd want to compare NULL modes.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 53885968bdaf..213b11ea69b5 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -903,6 +903,12 @@ EXPORT_SYMBOL(drm_mode_duplicate);
  */
 bool drm_mode_equal(const struct drm_display_mode *mode1, const struct drm_display_mode *mode2)
 {
+        if (!mode1 && !mode2)
+                return true;
+
+        if (!mode1 || !mode2)
+                return false;
+
         /* do clock check convert to PICOS so fb modes get matched
          * the same */
         if (mode1->clock && mode2->clock) {