drm/nv50: prevent multiple init tables being parsed at the same time

With DVI and DP plugged, the DVI clock change interrupts being run can
cause DP link training to fail.  This adds a spinlock around init table
parsing to prevent this.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_bios.c

@@ -3765,7 +3765,6 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 	 */
 
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
-	struct init_exec iexec = {true, false};
 	struct nvbios *bios = &dev_priv->VBIOS;
 	uint8_t *table = &bios->data[bios->display.script_table_ptr];
 	uint8_t *otable = NULL;
@@ -3845,8 +3844,6 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 		}
 	}
 
-	bios->display.output = dcbent;
-
 	if (pxclk == 0) {
 		script = ROM16(otable[6]);
 		if (!script) {
@@ -3855,7 +3852,7 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 		}
 
 		NV_TRACE(dev, "0x%04X: parsing output script 0\n", script);
-		parse_init_table(bios, script, &iexec);
+		nouveau_bios_run_init_table(dev, script, dcbent);
 	} else
 	if (pxclk == -1) {
 		script = ROM16(otable[8]);
@@ -3865,7 +3862,7 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 		}
 
 		NV_TRACE(dev, "0x%04X: parsing output script 1\n", script);
-		parse_init_table(bios, script, &iexec);
+		nouveau_bios_run_init_table(dev, script, dcbent);
 	} else
 	if (pxclk == -2) {
 		if (table[4] >= 12)
@@ -3878,7 +3875,7 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 		}
 
 		NV_TRACE(dev, "0x%04X: parsing output script 2\n", script);
-		parse_init_table(bios, script, &iexec);
+		nouveau_bios_run_init_table(dev, script, dcbent);
 	} else
 	if (pxclk > 0) {
 		script = ROM16(otable[table[4] + i*6 + 2]);
@@ -3890,7 +3887,7 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 		}
 
 		NV_TRACE(dev, "0x%04X: parsing clock script 0\n", script);
-		parse_init_table(bios, script, &iexec);
+		nouveau_bios_run_init_table(dev, script, dcbent);
 	} else
 	if (pxclk < 0) {
 		script = ROM16(otable[table[4] + i*6 + 4]);
@@ -3902,7 +3899,7 @@ nouveau_bios_run_display_table(struct drm_device *dev, struct dcb_entry *dcbent,
 		}
 
 		NV_TRACE(dev, "0x%04X: parsing clock script 1\n", script);
-		parse_init_table(bios, script, &iexec);
+		nouveau_bios_run_init_table(dev, script, dcbent);
 	}
 
 	return 0;
@@ -5864,10 +5861,13 @@ nouveau_bios_run_init_table(struct drm_device *dev, uint16_t table,
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	struct nvbios *bios = &dev_priv->VBIOS;
 	struct init_exec iexec = { true, false };
+	unsigned long flags;
 
+	spin_lock_irqsave(&bios->lock, flags);
 	bios->display.output = dcbent;
 	parse_init_table(bios, table, &iexec);
 	bios->display.output = NULL;
+	spin_unlock_irqrestore(&bios->lock, flags);
 }
 
 static bool NVInitVBIOS(struct drm_device *dev)
@@ -5876,6 +5876,7 @@ static bool NVInitVBIOS(struct drm_device *dev)
 	struct nvbios *bios = &dev_priv->VBIOS;
 
 	memset(bios, 0, sizeof(struct nvbios));
+	spin_lock_init(&bios->lock);
 	bios->dev = dev;
 
 	if (!NVShadowVBIOS(dev, bios->data))

drivers/gpu/drm/nouveau/nouveau_bios.h

@@ -205,6 +205,8 @@ struct nvbios {
 	struct drm_device *dev;
 	struct nouveau_bios_info pub;
 
+	spinlock_t lock;
+
 	uint8_t data[NV_PROM_SIZE];
 	unsigned int length;
 	bool execute;