2 files changed, 16 insertions, 2 deletions

diff --git a/Documentation/hwmon/tmp421 b/Documentation/hwmon/tmp421
index 0cf07f824741..d0e77143077f 100644
--- a/Documentation/hwmon/tmp421
+++ b/Documentation/hwmon/tmp421
@@ -8,11 +8,11 @@ Supported chips:
     Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp421.html
   * Texas Instruments TMP422
     Prefix: 'tmp422'
-    Addresses scanned: I2C 0x2a, 0x4c, 0x4d, 0x4e and 0x4f
+    Addresses scanned: I2C 0x4c, 0x4d, 0x4e and 0x4f
     Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp421.html
   * Texas Instruments TMP423
     Prefix: 'tmp423'
-    Addresses scanned: I2C 0x2a, 0x4c, 0x4d, 0x4e and 0x4f
+    Addresses scanned: I2C 0x4c and 0x4d
     Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp421.html
 
 Authors:
diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
index 7bab7a9bedc6..9438c1bd5d59 100644
--- a/drivers/hwmon/tmp421.c
+++ b/drivers/hwmon/tmp421.c
@@ -42,6 +42,7 @@ static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
 enum chips { tmp421, tmp422, tmp423 };
 
 /* The TMP421 registers */
+#define TMP421_STATUS_REG                       0x08
 #define TMP421_CONFIG_REG_1                     0x09
 #define TMP421_CONVERSION_RATE_REG              0x0B
 #define TMP421_MANUFACTURER_ID_REG              0xFE
@@ -235,6 +236,7 @@ static int tmp421_detect(struct i2c_client *client,
         enum chips kind;
         struct i2c_adapter *adapter = client->adapter;
         const char *names[] = { "TMP421", "TMP422", "TMP423" };
+        int addr = client->addr;
         u8 reg;
 
         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
@@ -244,15 +246,27 @@ static int tmp421_detect(struct i2c_client *client,
         if (reg != TMP421_MANUFACTURER_ID)
                 return -ENODEV;
 
+        reg = i2c_smbus_read_byte_data(client, TMP421_CONVERSION_RATE_REG);
+        if (reg & 0xf8)
+                return -ENODEV;
+
+        reg = i2c_smbus_read_byte_data(client, TMP421_STATUS_REG);
+        if (reg & 0x7f)
+                return -ENODEV;
+
         reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
         switch (reg) {
         case TMP421_DEVICE_ID:
                 kind = tmp421;
                 break;
         case TMP422_DEVICE_ID:
+                if (addr == 0x2a)
+                        return -ENODEV;
                 kind = tmp422;
                 break;
         case TMP423_DEVICE_ID:
+                if (addr != 0x4c && addr != 0x4d)
+                        return -ENODEV;
                 kind = tmp423;
                 break;
         default: