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

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 26b5647..47ad742 100644 (file)
--- 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;