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>

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -555,7 +555,7 @@ struct nouveau_pm_engine {
 
 	int  (*clocks_get)(struct drm_device *, struct nouveau_pm_level *);
 	void *(*clocks_pre)(struct drm_device *, struct nouveau_pm_level *);
-	void (*clocks_set)(struct drm_device *, void *);
+	int (*clocks_set)(struct drm_device *, void *);
 
 	int (*voltage_get)(struct drm_device *);
 	int (*voltage_set)(struct drm_device *, int voltage);

drivers/gpu/drm/nouveau/nouveau_pm.h

@@ -55,7 +55,7 @@ void nv04_pm_clock_set(struct drm_device *, void *);
 /* nv40_pm.c */
 int nv40_pm_clocks_get(struct drm_device *, struct nouveau_pm_level *);
 void *nv40_pm_clocks_pre(struct drm_device *, struct nouveau_pm_level *);
-void nv40_pm_clocks_set(struct drm_device *, void *);
+int nv40_pm_clocks_set(struct drm_device *, void *);
 int nv40_pm_pwm_get(struct drm_device *, struct dcb_gpio_entry *, u32*, u32*);
 int nv40_pm_pwm_set(struct drm_device *, struct dcb_gpio_entry *, u32, u32);
 
@@ -70,7 +70,7 @@ int nv50_pm_pwm_set(struct drm_device *, struct dcb_gpio_entry *, u32, u32);
 /* nva3_pm.c */
 int nva3_pm_clocks_get(struct drm_device *, struct nouveau_pm_level *);
 void *nva3_pm_clocks_pre(struct drm_device *, struct nouveau_pm_level *);
-void nva3_pm_clocks_set(struct drm_device *, void *);
+int nva3_pm_clocks_set(struct drm_device *, void *);
 
 /* nvc0_pm.c */
 int nvc0_pm_clocks_get(struct drm_device *, struct nouveau_pm_level *);

drivers/gpu/drm/nouveau/nv40_pm.c

@@ -222,7 +222,7 @@ nv40_pm_gr_idle(void *data)
 	return true;
 }
 
-void
+int
 nv40_pm_clocks_set(struct drm_device *dev, void *pre_state)
 {
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
@@ -231,7 +231,7 @@ nv40_pm_clocks_set(struct drm_device *dev, void *pre_state)
 	struct bit_entry M;
 	u32 crtc_mask = 0;
 	u8 sr1[2];
-	int i;
+	int i, ret = -EAGAIN;
 
 	/* determine which CRTCs are active, fetch VGA_SR1 for each */
 	for (i = 0; i < 2; i++) {
@@ -263,6 +263,8 @@ nv40_pm_clocks_set(struct drm_device *dev, void *pre_state)
 	if (!nv_wait_cb(dev, nv40_pm_gr_idle, dev))
 		goto resume;
 
+	ret = 0;
+
 	/* set engine clocks */
 	nv_mask(dev, 0x00c040, 0x00000333, 0x00000000);
 	nv_wr32(dev, 0x004004, info->npll_coef);
@@ -345,6 +347,7 @@ nv40_pm_clocks_set(struct drm_device *dev, void *pre_state)
 	spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
 
 	kfree(info);
+	return ret;
 }
 
 int

drivers/gpu/drm/nouveau/nva3_pm.c

@@ -287,12 +287,13 @@ nva3_pm_grcp_idle(void *data)
 	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 @@ nva3_pm_clocks_set(struct drm_device *dev, void *pre_state)
 		nv_wr32(dev, 0x100210, 0x80000000);
 	}
 
+	ret = 0;
+
 cleanup:
 	/* unfreeze PFIFO */
 	nv_mask(dev, 0x002504, 0x00000001, 0x00000000);
@@ -339,4 +342,5 @@ nva3_pm_clocks_set(struct drm_device *dev, void *pre_state)
 		nv_mask(dev, 0x400824, 0x10000000, 0x10000000);
 	spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
 	kfree(info);
+	return ret;
 }