drm/nouveau/kms: reference vblank for crtc during pageflip.

Need to drm_vblank_get/put() the crtc involved in a
pending pageflip, or we might not get vblank irqs and
updates of vblank counts and timestamps for pageflip
events and flip completion.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 26b5647188ef..47ad74255bf1 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -736,6 +736,9 @@ nouveau_crtc_page_flip(struct drm_crtc *crtc, struct drm_framebuffer *fb,
                   fb->bits_per_pixel, fb->pitches[0], crtc->x, crtc->y,
                   new_bo->bo.offset };
 
+        /* Keep vblanks on during flip, for the target crtc of this flip */
+        drm_vblank_get(dev, nouveau_crtc(crtc)->index);
+
         /* Emit a page flip */
         if (nv_device(drm->device)->card_type >= NV_50) {
                 ret = nv50_display_flip_next(crtc, fb, chan, swap_interval);
@@ -779,6 +782,7 @@ nouveau_crtc_page_flip(struct drm_crtc *crtc, struct drm_framebuffer *fb,
         return 0;
 
 fail_unreserve:
+        drm_vblank_put(dev, nouveau_crtc(crtc)->index);
         ttm_bo_unreserve(&old_bo->bo);
 fail_unpin:
         mutex_unlock(&chan->cli->mutex);
@@ -817,6 +821,9 @@ nouveau_finish_page_flip(struct nouveau_channel *chan,
                 drm_send_vblank_event(dev, crtcid, s->event);
         }
 
+        /* Give up ownership of vblank for page-flipped crtc */
+        drm_vblank_put(dev, s->crtc);
+
         list_del(&s->head);
         if (ps)
                 *ps = *s;