drm/msm/mdp5: Avoid flushing registers when CRTC is disabled

When a CRTC is disabled, no CTL is allocated to it (CRTC->ctl == NULL);
in that case we should not try to FLUSH registers and do nothing instead.

This can happen when we try to move a cursor but the CRTC's CTL
(CONTROL) has not been allocated yet (inactive CRTC).
It can also happens when we .atomic_check()/.atomic_flush() on a
disabled CRTC.

A CTL needs to be kept as long as the CRTC is alive. Releasing it
after the last VBlank is safer than in .atomic_flush().

Signed-off-by: Stephane Viau <sviau@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

1 files changed, 19 insertions, 7 deletions

diff --git a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_crtc.c b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_crtc.c
index 946b71b6e608..2aeae7351621 100644
--- a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_crtc.c
+++ b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_crtc.c
@@ -103,8 +103,8 @@ static void crtc_flush_all(struct drm_crtc *crtc)
         struct drm_plane *plane;
         uint32_t flush_mask = 0;
 
-        /* we could have already released CTL in the disable path: */
-        if (!mdp5_crtc->ctl)
+        /* this should not happen: */
+        if (WARN_ON(!mdp5_crtc->ctl))
                 return;
 
         drm_atomic_crtc_for_each_plane(plane, crtc) {
@@ -143,6 +143,11 @@ static void complete_flip(struct drm_crtc *crtc, struct drm_file *file)
         drm_atomic_crtc_for_each_plane(plane, crtc) {
                 mdp5_plane_complete_flip(plane);
         }
+
+        if (mdp5_crtc->ctl && !crtc->state->enable) {
+                mdp5_ctl_release(mdp5_crtc->ctl);
+                mdp5_crtc->ctl = NULL;
+        }
 }
 
 static void unref_cursor_worker(struct drm_flip_work *work, void *val)
@@ -386,14 +391,17 @@ static void mdp5_crtc_atomic_flush(struct drm_crtc *crtc)
         mdp5_crtc->event = crtc->state->event;
         spin_unlock_irqrestore(&dev->event_lock, flags);
 
+        /*
+         * If no CTL has been allocated in mdp5_crtc_atomic_check(),
+         * it means we are trying to flush a CRTC whose state is disabled:
+         * nothing else needs to be done.
+         */
+        if (unlikely(!mdp5_crtc->ctl))
+                return;
+
         blend_setup(crtc);
         crtc_flush_all(crtc);
         request_pending(crtc, PENDING_FLIP);
-
-        if (mdp5_crtc->ctl && !crtc->state->enable) {
-                mdp5_ctl_release(mdp5_crtc->ctl);
-                mdp5_crtc->ctl = NULL;
-        }
 }
 
 static int mdp5_crtc_set_property(struct drm_crtc *crtc,
@@ -495,6 +503,10 @@ static int mdp5_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
         uint32_t roi_h;
         unsigned long flags;
 
+        /* In case the CRTC is disabled, just drop the cursor update */
+        if (unlikely(!crtc->state->enable))
+                return 0;
+
         x = (x > 0) ? x : 0;
         y = (y > 0) ? y : 0;