Hi Per,
On Wed, 2011-05-25 at 13:48 -0400, Per DalÃn wrote:
> Made the improvement for the detection schema suggested by Guenter Roeck.
> ---
> Check for non-existing registers, registers 0x04, 0x06 and 0xff, which
> are supported by other Maxim chips. Reading such registers returns the
> previously read value.
>
> Signed-off-by: Per Dalen <per.dalen@xxxxxxxxxxxx>
> ---
>
> diff --git a/drivers/hwmon/max6642.c b/drivers/hwmon/max6642.c
> index 0f9fc40..69c7f9e 100644
> --- a/drivers/hwmon/max6642.c
> +++ b/drivers/hwmon/max6642.c
> @@ -64,6 +64,14 @@ static const unsigned short normal_i2c[] = {
> #define MAX6642_REG_W_REMOTE_HIGH 0x0D
>
> /*
> + * Registers for detection tests, these registers isn't pressent and
> + * will only show the last valid register read.
> + */
> +#define MAX6642_REG_R_DUMMY_1 0x04
> +#define MAX6642_REG_R_DUMMY_2 0x06
> +#define MAX6642_REG_R_DUMMY_3 0xFF
> +
> +/*
> * Conversions
> */
>
> @@ -126,14 +134,16 @@ static int max6642_detect(struct i2c_client *client,
> struct i2c_board_info *info)
> {
> struct i2c_adapter *adapter = client->adapter;
> - u8 reg_config, reg_status, man_id;
> + u8 reg_config, reg_status, man_id, dummy_reg1, dummy_reg2;
>
> if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> return -ENODEV;
>
> /* identification */
> man_id = i2c_smbus_read_byte_data(client, MAX6642_REG_R_MAN_ID);
> - if (man_id != 0x4D)
> + dummy_reg1 = i2c_smbus_read_byte_data(client, MAX6642_REG_R_DUMMY_1);
> + if ((man_id != 0x4D) &&
> + (man_id != dummy_reg1))
Please drop all the unnecessary () and the unnecessary line break. Also,
I think the logic is wrong. It should be
if (man_id != 0x4d || man_id != dummy_reg1)
> return -ENODEV;
>
> /*
> @@ -142,9 +152,13 @@ static int max6642_detect(struct i2c_client *client,
> * zero in the status register.
> */
> reg_config = i2c_smbus_read_byte_data(client, MAX6642_REG_R_CONFIG);
> + dummy_reg1 = i2c_smbus_read_byte_data(client, MAX6642_REG_R_DUMMY_2);
> reg_status = i2c_smbus_read_byte_data(client, MAX6642_REG_R_STATUS);
> - if (((reg_config & 0x0f) != 0x00) ||
> - ((reg_status & 0x2b) != 0x00))
> + dummy_reg2 = i2c_smbus_read_byte_data(client, MAX6642_REG_R_DUMMY_3);
> + if ((reg_config & 0x0f) != 0x00 ||
> + (reg_status & 0x2b) != 0x00 ||
> + reg_config != dummy_reg1 ||
> + reg_status != dummy_reg2)
Please remove unnecessary line breaks.
I think it is better to read all dummy registers right after reading
man_id. This way we know for sure that the MAX6642 will return 0x4d when
reading those registers, and you can check each of the registers against
man_id in the first if statement above.
Thanks,
Guenter
_______________________________________________
lm-sensors mailing list
lm-sensors@xxxxxxxxxxxxxx
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
