drm/nouveau/kms/nv04-nv40: fix pageflip events via special case.

kleinerm · Ben Skeggs · commit af4870e40612 · 2014-06-10T16:08:09.000+10:00
Cards with nv04 display engine can't reliably use vblank
counts and timestamps computed via drm_handle_vblank(), as
the function gets invoked after sending the pageflip events.

Fix this by defaulting to the old crtcid = -1 fallback path
on &lt;= NV-50 cards, and only using the precise path on NV-50
and later.

Signed-off-by: Mario Kleiner &lt;mario.kleiner.de@gmail.com&gt;
Signed-off-by: Ben Skeggs &lt;bskeggs@redhat.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # 3.13+
diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -798,6 +798,7 @@ nouveau_finish_page_flip(struct nouveau_channel *chan,
 	struct drm_device *dev = drm->dev;
 	struct nouveau_page_flip_state *s;
 	unsigned long flags;
+	int crtcid = -1;
 
 	spin_lock_irqsave(&dev->event_lock, flags);
 
@@ -808,8 +809,13 @@ nouveau_finish_page_flip(struct nouveau_channel *chan,
 	}
 
 	s = list_first_entry(&fctx->flip, struct nouveau_page_flip_state, head);
-	if (s->event)
-		drm_send_vblank_event(dev, s->crtc, s->event);
+	if (s->event) {
+		/* Vblank timestamps/counts are only correct on >= NV-50 */
+		if (nv_device(drm->device)->card_type >= NV_50)
+			crtcid = s->crtc;
+
+		drm_send_vblank_event(dev, crtcid, s->event);
+	}
 
 	list_del(&s->head);
 	if (ps)
