[lm-sensors] Use of swab16() in drivers/hwmon/*.c

[lm-sensors] Use of swab16() in drivers/hwmon/*.c

[Roland Stigge]

Hi,

I wonder about a specific use of swab16() in several files
in drivers/hwmon/.

Consider ds1621.c: We get big endian words from
i2c_smbus_read_word_data(). To use it on a little endian arch, the
driver uses swab16() for conversion by swapping bytes unconditionally.

IMHO this is not suitable on a big endian architecture. Shouldn't it be
sth. like be16_to_cpu()?

Thanks in advance.

bye,
  Roland

_______________________________________________
lm-sensors mailing list
lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

Re: [lm-sensors] Use of swab16() in drivers/hwmon/*.c

[Jean Delvare]

Hallo Roland,

On Fri, 07 Jan 2011 11:37:15 +0100, Roland Stigge wrote:
> I wonder about a specific use of swab16() in several files
> in drivers/hwmon/.
> 
> Consider ds1621.c: We get big endian words from
> i2c_smbus_read_word_data(). To use it on a little endian arch, the
> driver uses swab16() for conversion by swapping bytes unconditionally.
> 
> IMHO this is not suitable on a big endian architecture. Shouldn't it be
> sth. like be16_to_cpu()?

This has nothing to do with the host's endianess. This has to do with
the fact that the SMBus specification says that words are sent low byte
first but almost all hardware monitoring devices send the high byte
first (because it makes a lot more sense.)

-- 
Jean Delvare

_______________________________________________
lm-sensors mailing list
lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

Re: [lm-sensors] Use of swab16() in drivers/hwmon/*.c

[Roland Stigge]

Hi,

On 01/07/2011 11:59 AM, Jean Delvare wrote:
> This has nothing to do with the host's endianess. This has to do with
> the fact that the SMBus specification says that words are sent low byte
> first but almost all hardware monitoring devices send the high byte
> first (because it makes a lot more sense.)

Thanks! I just ignored that the word implementation of Linux' SMBus
(I2C_SMBUS_WORD_DATA etc.) already takes care of that.

bye,
  Roland

_______________________________________________
lm-sensors mailing list
lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors