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@xxxxxxxxxxxx>
Cc: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
Cc: Robert Casanova <robertcasanova@xxxxxxxxxxxxxx>
---
drivers/hwmon/lm73.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
--- linux-3.1-rc4.orig/drivers/hwmon/lm73.c 2011-07-22 04:17:23.000000000 +0200
+++ linux-3.1-rc4/drivers/hwmon/lm73.c 2011-08-30 21:13:46.000000000 +0200
@@ -150,17 +150,31 @@ static int lm73_detect(struct i2c_client
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);
--
Jean Delvare
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