drm/nouveau/pm: make clocks_set return an error code clocks_set can fail.

Reporting an error is better than silently refusing to reclock.

V2: Use the same logic on nv40

Signed-off-by: Martin Peres <martin.peres@labri.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nva3_pm.c b/drivers/gpu/drm/nouveau/nva3_pm.c
index 618c144..9e636e6 100644
--- a/drivers/gpu/drm/nouveau/nva3_pm.c
+++ b/drivers/gpu/drm/nouveau/nva3_pm.c
@@ -287,12 +287,13 @@
 	return false;
 }
 
-void
+int
 nva3_pm_clocks_set(struct drm_device *dev, void *pre_state)
 {
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	struct nva3_pm_state *info = pre_state;
 	unsigned long flags;
+	int ret = -EAGAIN;
 
 	/* prevent any new grctx switches from starting */
 	spin_lock_irqsave(&dev_priv->context_switch_lock, flags);
@@ -328,6 +329,8 @@
 		nv_wr32(dev, 0x100210, 0x80000000);
 	}
 
+	ret = 0;
+
 cleanup:
 	/* unfreeze PFIFO */
 	nv_mask(dev, 0x002504, 0x00000001, 0x00000000);
@@ -339,4 +342,5 @@
 		nv_mask(dev, 0x400824, 0x10000000, 0x10000000);
 	spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
 	kfree(info);
+	return ret;
 }