drm/vc4: Fix drm_vblank_put/get imbalance in page flip path.

The async page flip path was missing drm_crtc_vblank_get/put
completely. The sync flip path was missing a vblank put, so async
flips only reported proper pageflip completion events by chance,
and vblank irq's never turned off after a first vsync'ed page flip
until system reboot.

Tested against Raspian kernel 4.4.8 tree on RPi 2B.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Fixes: b501bacc6060 ("drm/vc4: Add support for async pageflips.")

diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
index 904d075..e9befb6 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -506,6 +506,7 @@ static void vc4_crtc_handle_page_flip(struct vc4_crtc *vc4_crtc)
        if (vc4_crtc->event) {
                drm_crtc_send_vblank_event(crtc, vc4_crtc->event);
                vc4_crtc->event = NULL;
+               drm_crtc_vblank_put(crtc);
        }
        spin_unlock_irqrestore(&dev->event_lock, flags);
 }
@@ -556,6 +557,7 @@ vc4_async_page_flip_complete(struct vc4_seqno_cb *cb)
                spin_unlock_irqrestore(&dev->event_lock, flags);
        }
 
+       drm_crtc_vblank_put(crtc);
        drm_framebuffer_unreference(flip_state->fb);
        kfree(flip_state);
 
@@ -598,6 +600,8 @@ static int vc4_async_page_flip(struct drm_crtc *crtc,
                return ret;
        }
 
+       WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+
        /* Immediately update the plane's legacy fb pointer, so that later
         * modeset prep sees the state that will be present when the semaphore
         * is released.