1 files changed, 57 insertions, 7 deletions

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 97f338b123..25bc7b8d98 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -34,6 +34,7 @@ static int smbus_do_alert(struct device *dev, void *addrp)
 	struct i2c_client *client = i2c_verify_client(dev);
 	struct alert_data *data = addrp;
 	struct i2c_driver *driver;
+	int ret;
 
 	if (!client || client->addr != data->addr)
 		return 0;
@@ -47,16 +48,47 @@ static int smbus_do_alert(struct device *dev, void *addrp)
 	device_lock(dev);
 	if (client->dev.driver) {
 		driver = to_i2c_driver(client->dev.driver);
-		if (driver->alert)
+		if (driver->alert) {
+			/* Stop iterating after we find the device */
 			driver->alert(client, data->type, data->data);
-		else
+			ret = -EBUSY;
+		} else {
 			dev_warn(&client->dev, "no driver alert()!\n");
-	} else
+			ret = -EOPNOTSUPP;
+		}
+	} else {
 		dev_dbg(&client->dev, "alert with no driver\n");
+		ret = -ENODEV;
+	}
+	device_unlock(dev);
+
+	return ret;
+}
+
+/* Same as above, but call back all drivers with alert handler */
+
+static int smbus_do_alert_force(struct device *dev, void *addrp)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	struct alert_data *data = addrp;
+	struct i2c_driver *driver;
+
+	if (!client || (client->flags & I2C_CLIENT_TEN))
+		return 0;
+
+	/*
+	 * Drivers should either disable alerts, or provide at least
+	 * a minimal handler. Lock so the driver won't change.
+	 */
+	device_lock(dev);
+	if (client->dev.driver) {
+		driver = to_i2c_driver(client->dev.driver);
+		if (driver->alert)
+			driver->alert(client, data->type, data->data);
+	}
 	device_unlock(dev);
 
-	/* Stop iterating after we find the device */
-	return -EBUSY;
+	return 0;
 }
 
 /*
@@ -67,6 +99,7 @@ static irqreturn_t smbus_alert(int irq, void *d)
 {
 	struct i2c_smbus_alert *alert = d;
 	struct i2c_client *ara;
+	unsigned short prev_addr = I2C_CLIENT_END; /* Not a valid address */
 
 	ara = alert->ara;
 
@@ -94,8 +127,25 @@ static irqreturn_t smbus_alert(int irq, void *d)
 			data.addr, data.data);
 
 		/* Notify driver for the device which issued the alert */
-		device_for_each_child(&ara->adapter->dev, &data,
-				      smbus_do_alert);
+		status = device_for_each_child(&ara->adapter->dev, &data,
+					       smbus_do_alert);
+		/*
+		 * If we read the same address more than once, and the alert
+		 * was not handled by a driver, it won't do any good to repeat
+		 * the loop because it will never terminate. Try again, this
+		 * time calling the alert handlers of all devices connected to
+		 * the bus, and abort the loop afterwards. If this helps, we
+		 * are all set. If it doesn't, there is nothing else we can do,
+		 * so we might as well abort the loop.
+		 * Note: This assumes that a driver with alert handler handles
+		 * the alert properly and clears it if necessary.
+		 */
+		if (data.addr == prev_addr && status != -EBUSY) {
+			device_for_each_child(&ara->adapter->dev, &data,
+					      smbus_do_alert_force);
+			break;
+		}
+		prev_addr = data.addr;
 	}
 
 	return IRQ_HANDLED;