Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c fixes from Wolfram Sang:
 "An I2C core fix to prevent a use-after-free in a rare error path,
  and an I2C ACPI addition to work around broken HW/firmware related
  to touchscreens"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: core: fix use after free in of_i2c_notify
  i2c: acpi: Force bus speed to 400KHz if a Silead touchscreen is present

drivers/i2c/i2c-core-acpi.c

@@ -39,6 +39,7 @@ struct i2c_acpi_lookup {
 	int index;
 	u32 speed;
 	u32 min_speed;
+	u32 force_speed;
 };
 
 /**
@@ -285,6 +286,19 @@ i2c_acpi_match_device(const struct acpi_device_id *matches,
 	return acpi_match_device(matches, &client->dev);
 }
 
+static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = {
+	/*
+	 * These Silead touchscreen controllers only work at 400KHz, for
+	 * some reason they do not work at 100KHz. On some devices the ACPI
+	 * tables list another device at their bus as only being capable
+	 * of 100KHz, testing has shown that these other devices work fine
+	 * at 400KHz (as can be expected of any recent i2c hw) so we force
+	 * the speed of the bus to 400 KHz if a Silead device is present.
+	 */
+	{ "MSSL1680", 0 },
+	{}
+};
+
 static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 					   void *data, void **return_value)
 {
@@ -303,6 +317,9 @@ static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 	if (lookup->speed <= lookup->min_speed)
 		lookup->min_speed = lookup->speed;
 
+	if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0)
+		lookup->force_speed = 400000;
+
 	return AE_OK;
 }
 
@@ -340,7 +357,16 @@ u32 i2c_acpi_find_bus_speed(struct device *dev)
 		return 0;
 	}
 
-	return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0;
+	if (lookup.force_speed) {
+		if (lookup.force_speed != lookup.min_speed)
+			dev_warn(dev, FW_BUG "DSDT uses known not-working I2C bus speed %d, forcing it to %d\n",
+				 lookup.min_speed, lookup.force_speed);
+		return lookup.force_speed;
+	} else if (lookup.min_speed != UINT_MAX) {
+		return lookup.min_speed;
+	} else {
+		return 0;
+	}
 }
 EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);
 

drivers/i2c/i2c-core-of.c

@@ -245,14 +245,14 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
 		}
 
 		client = of_i2c_register_device(adap, rd->dn);
-		put_device(&adap->dev);
-
 		if (IS_ERR(client)) {
 			dev_err(&adap->dev, "failed to create client for '%pOF'\n",
 				 rd->dn);
+			put_device(&adap->dev);
 			of_node_clear_flag(rd->dn, OF_POPULATED);
 			return notifier_from_errno(PTR_ERR(client));
 		}
+		put_device(&adap->dev);
 		break;
 	case OF_RECONFIG_CHANGE_REMOVE:
 		/* already depopulated? */