From 24d6e2a89a1ff0a035f163a83a2812a3192083b6 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Fri, 4 Nov 2011 12:00:46 +0100 Subject: [PATCH] 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 Acked-by: Guenter Roeck Cc: Robert Casanova --- drivers/hwmon/lm73.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/hwmon/lm73.c b/drivers/hwmon/lm73.c index 29b9030d42c3..24be17608fbb 100644 --- a/drivers/hwmon/lm73.c +++ b/drivers/hwmon/lm73.c @@ -150,17 +150,31 @@ static int lm73_detect(struct i2c_client *new_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);