drm: rcar-du: Move group locking inside rcar_du_crtc_update_planes()

Only the planes to CRTCs association control register DPTSR needs to be
protected by custom locking, don't hold the mutex around the whole code.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

1 files changed, 3 insertions, 7 deletions

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index 29bbb44eecc9..8459aaee8add 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -252,8 +252,6 @@ static void rcar_du_crtc_update_planes(struct rcar_du_crtc *rcrtc)
          * with superposition controller 2.
          */
         if (rcrtc->index % 2) {
-                u32 value = rcar_du_group_read(rcrtc->group, DPTSR);
-
                 /* The DPTSR register is updated when the display controller is
                  * stopped. We thus need to restart the DU. Once again, sorry
                  * for the flicker. One way to mitigate the issue would be to
@@ -261,11 +259,13 @@ static void rcar_du_crtc_update_planes(struct rcar_du_crtc *rcrtc)
                  * split, or through a module parameter). Flicker would then
                  * occur only if we need to break the pre-association.
                  */
-                if (value != dptsr) {
+                mutex_lock(&rcrtc->group->planes.lock);
+                if (rcar_du_group_read(rcrtc->group, DPTSR) != dptsr) {
                         rcar_du_group_write(rcrtc->group, DPTSR, dptsr);
                         if (rcrtc->group->used_crtcs)
                                 rcar_du_group_restart(rcrtc->group);
                 }
+                mutex_unlock(&rcrtc->group->planes.lock);
         }
 
         rcar_du_group_write(rcrtc->group, rcrtc->index % 2 ? DS2PR : DS1PR,
@@ -435,9 +435,7 @@ void rcar_du_crtc_resume(struct rcar_du_crtc *rcrtc)
                 rcar_du_plane_setup(plane);
         }
 
-        mutex_lock(&rcrtc->group->planes.lock);
         rcar_du_crtc_update_planes(rcrtc);
-        mutex_unlock(&rcrtc->group->planes.lock);
 }
 
 /* -----------------------------------------------------------------------------
@@ -501,9 +499,7 @@ static void rcar_du_crtc_atomic_flush(struct drm_crtc *crtc)
 {
         struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
 
-        mutex_lock(&rcrtc->group->planes.lock);
         rcar_du_crtc_update_planes(rcrtc);
-        mutex_unlock(&rcrtc->group->planes.lock);
 }
 
 static const struct drm_crtc_helper_funcs crtc_helper_funcs = {