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hwmon: (lm73) Make detection less problematic

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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>
This commit is contained in:
Jean Delvare 2011-11-04 12:00:46 +01:00 committed by Jean Delvare
parent 746cdfbf01
commit 24d6e2a89a
1 changed files with 18 additions and 4 deletions
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22
drivers/hwmon/lm73.c
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@ -150,17 +150,31 @@ static int lm73_detect(struct i2c_client *new_client,
struct i2c_board_info *info) struct i2c_board_info *info)
{ {
struct i2c_adapter *adapter = new_client->adapter; struct i2c_adapter *adapter = new_client->adapter;
u16 id; int id, ctrl, conf;
u8 ctrl;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA)) I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV; 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 */ /* Check device ID */
id = i2c_smbus_read_word_data(new_client, LM73_REG_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 < 0 || id != LM73_ID)
if ((id != LM73_ID) || (ctrl & 0x10))
return -ENODEV; return -ENODEV;
strlcpy(info->type, "lm73", I2C_NAME_SIZE); strlcpy(info->type, "lm73", I2C_NAME_SIZE);