drm/vc4: Resolve the vblank warnings on mode switching

The details over when and how a driver is to service the
vblank events are sketchy, and the fkms driver was triggering
a kernel warning every time the crtc was enabled or disabled.

Copy the event handling as used by the vc4-kms driver slightly
more closely, and we avoid the warnings.

https://github.com/raspberrypi/linux/issues/3020

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>

diff --git a/drivers/gpu/drm/vc4/vc4_firmware_kms.c b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
index fa8a538..d9779b9 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
@@ -964,6 +964,7 @@ static void vc4_crtc_mode_set_nofb(struct drm_crtc *crtc)
 
 static void vc4_crtc_disable(struct drm_crtc *crtc, struct drm_crtc_state *old_state)
 {
+       struct drm_device *dev = crtc->dev;
        struct drm_plane *plane;
 
        DRM_DEBUG_KMS("[CRTC:%d] vblanks off.\n",
@@ -979,6 +980,35 @@ static void vc4_crtc_disable(struct drm_crtc *crtc, struct drm_crtc_state *old_s
 
        drm_atomic_crtc_for_each_plane(plane, crtc)
                vc4_plane_atomic_disable(plane, plane->state);
+
+       /*
+        * Make sure we issue a vblank event after disabling the CRTC if
+        * someone was waiting it.
+        */
+       if (crtc->state->event) {
+               unsigned long flags;
+
+               spin_lock_irqsave(&dev->event_lock, flags);
+               drm_crtc_send_vblank_event(crtc, crtc->state->event);
+               crtc->state->event = NULL;
+               spin_unlock_irqrestore(&dev->event_lock, flags);
+       }
+}
+
+static void vc4_crtc_consume_event(struct drm_crtc *crtc)
+{
+       struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
+       struct drm_device *dev = crtc->dev;
+       unsigned long flags;
+
+       crtc->state->event->pipe = drm_crtc_index(crtc);
+
+       WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+
+       spin_lock_irqsave(&dev->event_lock, flags);
+       vc4_crtc->event = crtc->state->event;
+       crtc->state->event = NULL;
+       spin_unlock_irqrestore(&dev->event_lock, flags);
 }
 
 static void vc4_crtc_enable(struct drm_crtc *crtc, struct drm_crtc_state *old_state)
@@ -988,6 +1018,7 @@ static void vc4_crtc_enable(struct drm_crtc *crtc, struct drm_crtc_state *old_st
        DRM_DEBUG_KMS("[CRTC:%d] vblanks on.\n",
                      crtc->base.id);
        drm_crtc_vblank_on(crtc);
+       vc4_crtc_consume_event(crtc);
 
        /* Unblank the planes (if they're supposed to be displayed). */
        drm_atomic_crtc_for_each_plane(plane, crtc)
@@ -1059,23 +1090,10 @@ static int vc4_crtc_atomic_check(struct drm_crtc *crtc,
 static void vc4_crtc_atomic_flush(struct drm_crtc *crtc,
                                  struct drm_crtc_state *old_state)
 {
-       struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
-       struct drm_device *dev = crtc->dev;
-
        DRM_DEBUG_KMS("[CRTC:%d] crtc_atomic_flush.\n",
                      crtc->base.id);
-       if (crtc->state->event) {
-               unsigned long flags;
-
-               crtc->state->event->pipe = drm_crtc_index(crtc);
-
-               WARN_ON(drm_crtc_vblank_get(crtc) != 0);
-
-               spin_lock_irqsave(&dev->event_lock, flags);
-               vc4_crtc->event = crtc->state->event;
-               crtc->state->event = NULL;
-               spin_unlock_irqrestore(&dev->event_lock, flags);
-       }
+       if (crtc->state->active && old_state->active && crtc->state->event)
+               vc4_crtc_consume_event(crtc);
 }
 
 static void vc4_crtc_handle_page_flip(struct vc4_crtc *vc4_crtc)