On Thu, 26 May 2011 15:08:53 +0200, Per Dalén wrote:
> Changed according to the suggestions from Guenter Roeck:
>
> * Check the manufacturer ID directly. Fastens the test if it's not a
> Maxim chip.
> * Read the other non-existing registers after the manufacturer ID.
>
> ---
> 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..565b507 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
I don't even think you want defines for these. They don't exist! The
comment would be better placed right before the relevant piece of code.
> +
> +/*
> * Conversions
> */
>
> @@ -126,7 +134,7 @@ 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_reg;
>
> if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> return -ENODEV;
> @@ -136,6 +144,19 @@ static int max6642_detect(struct i2c_client *client,
> if (man_id != 0x4D)
> return -ENODEV;
>
> + /* sanity check */
> + dummy_reg = i2c_smbus_read_byte_data(client, MAX6642_REG_R_DUMMY_1);
> + if (dummy_reg != 0x4D)
> + return -ENODEV;
> +
> + dummy_reg = i2c_smbus_read_byte_data(client, MAX6642_REG_R_DUMMY_2);
> + if (dummy_reg != 0x4D)
> + return -ENODEV;
> +
> + dummy_reg = i2c_smbus_read_byte_data(client, MAX6642_REG_R_DUMMY_3);
> + if (dummy_reg != 0x4D)
> + return -ENODEV;
> +
Same as for sensors-detect, please do a second round of checks after
reading the config or status register. You may want to move the checks
to a small function to avoid repeating the code.
> /*
> * We read the config and status register, the 4 lower bits in the
> * config register should be zero and bit 5, 3, 1 and 0 should be
>
--
Jean Delvare
_______________________________________________
lm-sensors mailing list
lm-sensors@xxxxxxxxxxxxxx
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
