hwmon: (lm73) Make detection less problematic
Word reads can cause trouble with some I2C devices, so do as much
detection as we can using only byte reads, and only use a word read in
the end to confirm the positive match. Also properly handle read
errors.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Robert Casanova <robertcasanova@nanometrics.ca>
diff --git a/drivers/hwmon/lm73.c b/drivers/hwmon/lm73.c
index 29b9030..24be176 100644
--- a/drivers/hwmon/lm73.c
+++ b/drivers/hwmon/lm73.c
@@ -150,17 +150,31 @@
struct i2c_board_info *info)
{
struct i2c_adapter *adapter = new_client->adapter;
- u16 id;
- u8 ctrl;
+ int id, ctrl, conf;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV;
+ /*
+ * Do as much detection as possible with byte reads first, as word
+ * reads can confuse other devices.
+ */
+ ctrl = i2c_smbus_read_byte_data(new_client, LM73_REG_CTRL);
+ if (ctrl < 0 || (ctrl & 0x10))
+ return -ENODEV;
+
+ conf = i2c_smbus_read_byte_data(new_client, LM73_REG_CONF);
+ if (conf < 0 || (conf & 0x0c))
+ return -ENODEV;
+
+ id = i2c_smbus_read_byte_data(new_client, LM73_REG_ID);
+ if (id < 0 || id != (LM73_ID & 0xff))
+ return -ENODEV;
+
/* Check device ID */
id = i2c_smbus_read_word_data(new_client, LM73_REG_ID);
- ctrl = i2c_smbus_read_byte_data(new_client, LM73_REG_CTRL);
- if ((id != LM73_ID) || (ctrl & 0x10))
+ if (id < 0 || id != LM73_ID)
return -ENODEV;
strlcpy(info->type, "lm73", I2C_NAME_SIZE);