drm/radeon/kms: only change mode when coherent value changes.

On X startup we were getting a flicker where there shouldn't have been one.
the X DDX calls the kernel to set the properties to the same values (yes
it could be smarter), however the kernel was doing a pointless modeset then,
making my nice smooth boot ugly.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index 3fba50540f72..3bc20406d45b 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -287,6 +287,7 @@ int radeon_connector_set_property(struct drm_connector *connector, struct drm_pr
 
         if (property == rdev->mode_info.coherent_mode_property) {
                 struct radeon_encoder_atom_dig *dig;
+                bool new_coherent_mode;
 
                 /* need to find digital encoder on connector */
                 encoder = radeon_find_encoder(connector, DRM_MODE_ENCODER_TMDS);
@@ -299,8 +300,11 @@ int radeon_connector_set_property(struct drm_connector *connector, struct drm_pr
                         return 0;
 
                 dig = radeon_encoder->enc_priv;
-                dig->coherent_mode = val ? true : false;
-                radeon_property_change_mode(&radeon_encoder->base);
+                new_coherent_mode = val ? true : false;
+                if (dig->coherent_mode != new_coherent_mode) {
+                        dig->coherent_mode = new_coherent_mode;
+                        radeon_property_change_mode(&radeon_encoder->base);
+                }
         }
 
         if (property == rdev->mode_info.tv_std_property) {