Hi Guenter,
On Fri, 26 Aug 2011 09:19:02 -0700, Guenter Roeck wrote:
> Return values for functions reading/writing manufacturer specific registers are
> poorly explained. Add comments to improve documentation.
>
> Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
> ---
> drivers/hwmon/pmbus/pmbus.h | 18 ++++++++++++++++--
> 1 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> index a6ae20f..da90167 100644
> --- a/drivers/hwmon/pmbus/pmbus.h
> +++ b/drivers/hwmon/pmbus/pmbus.h
> @@ -134,8 +134,16 @@
> * Semantics:
> * Virtual registers are all word size.
> * READ registers are read-only; writes are either ignored or return an error.
> - * RESET registers are read/write. Reading returns zero (used for detection),
> - * writing any value causes the associated history to be reset.
> + * RESET registers are read/write. Reading reset registers returns zero
> + * (used for detection), writing any value causes the associated history to be
> + * reset.
> + * Virtual registers have to be handled in device specific driver code. Chip
> + * driver code returns non-negative register values if a virtual register is
> + * supported, or a negative error code if not. The chip driver may return
> + * -ENODATA or any other error code in this case, though an error code other
> + * than -ENODATA is handled more efficiently and thus preferred. Either case,
> + * the calling PMBus core code will abort if the chip driver returns an error
> + * code when reading or writing virtual registers.
The explanation below suggests that the code doesn't actually abort in
the -ENODATA case, but instead falls back to an alternative register
access?
> */
> #define PMBUS_VIRT_BASE 0x100
> #define PMBUS_VIRT_READ_TEMP_MIN (PMBUS_VIRT_BASE + 0)
> @@ -320,6 +328,12 @@ struct pmbus_driver_info {
> * The following functions map manufacturing specific register values
> * to PMBus standard register values. Specify only if mapping is
> * necessary.
> + * Function return the register value (read) or zero (write) if
"Functions return" or "Function returns".
> + * successful. A return value of -ENODATA indicates that there is no
> + * manufacturer specific register, but that a standard PMBus register
> + * may exist. Any other negative return value indicates that the
> + * register does not exist, and that no attempt should be made to read
> + * the standard register.
> */
> int (*read_byte_data)(struct i2c_client *client, int page, int reg);
> int (*read_word_data)(struct i2c_client *client, int page, int reg);
Other than this, looks good, thanks for adding this piece of
documentation.
Acked-by: Jean Delvare <khali@xxxxxxxxxxxx>
--
Jean Delvare
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