---

yaml
---
r: 293599
b: refs/heads/master
c: 8a8ed1f
h: refs/heads/master
i:
  293597: 657468e
  293595: 317b765
  293591: e85339a
  293583: 96ec1c5
  293567: 26128c4
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b1d7e4b41fd0f72ea8149056778db5d737739305
+refs/heads/master: 8a8ed1f5143b3df312e436ab15290e4a7ca6a559

trunk/drivers/gpu/drm/i915/i915_drv.h

@@ -313,6 +313,10 @@ typedef struct drm_i915_private {
 		u32 reg0;
 	} *gmbus;
 
+	/** gmbus_mutex protects against concurrent usage of the single hw gmbus
+	 * controller on different i2c buses. */
+	struct mutex gmbus_mutex;
+
 	struct pci_dev *bridge_dev;
 	struct intel_ring_buffer ring[I915_NUM_RINGS];
 	uint32_t next_seqno;

trunk/drivers/gpu/drm/i915/intel_i2c.c

@@ -233,11 +233,15 @@ gmbus_xfer(struct i2c_adapter *adapter,
 					       struct intel_gmbus,
 					       adapter);
 	struct drm_i915_private *dev_priv = adapter->algo_data;
-	int i, reg_offset;
+	int i, reg_offset, ret;
 
-	if (bus->force_bit)
-		return intel_i2c_quirk_xfer(dev_priv,
+	mutex_lock(&dev_priv->gmbus_mutex);
+
+	if (bus->force_bit) {
+		ret = intel_i2c_quirk_xfer(dev_priv,
 					    bus->force_bit, msgs, num);
+		goto out;
+	}
 
 	reg_offset = HAS_PCH_SPLIT(dev_priv->dev) ? PCH_GMBUS0 - GMBUS0 : 0;
 
@@ -321,7 +325,8 @@ gmbus_xfer(struct i2c_adapter *adapter,
 	 * start of the next xfer, till then let it sleep.
 	 */
 	I915_WRITE(GMBUS0 + reg_offset, 0);
-	return i;
+	ret = i;
+	goto out;
 
 timeout:
 	DRM_INFO("GMBUS timed out, falling back to bit banging on pin %d [%s]\n",
@@ -331,9 +336,12 @@ gmbus_xfer(struct i2c_adapter *adapter,
 	/* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
 	bus->force_bit = intel_gpio_create(dev_priv, bus->reg0 & 0xff);
 	if (!bus->force_bit)
-		return -ENOMEM;
-
-	return intel_i2c_quirk_xfer(dev_priv, bus->force_bit, msgs, num);
+		ret = -ENOMEM;
+	else
+		ret = intel_i2c_quirk_xfer(dev_priv, bus->force_bit, msgs, num);
+out:
+	mutex_unlock(&dev_priv->gmbus_mutex);
+	return ret;
 }
 
 static u32 gmbus_func(struct i2c_adapter *adapter)
@@ -380,6 +388,8 @@ int intel_setup_gmbus(struct drm_device *dev)
 	if (dev_priv->gmbus == NULL)
 		return -ENOMEM;
 
+	mutex_init(&dev_priv->gmbus_mutex);
+
 	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
 		struct intel_gmbus *bus = &dev_priv->gmbus[i];