Re: [lm-sensors] [PATCH] hwmon: (ads7828) Make sample interval configurable

From: Jean Delvare
Date: Tue Jan 27 2015 - 17:35:20 EST


On Tue, 27 Jan 2015 12:05:53 -0800, Guenter Roeck wrote:
> On Tue, Jan 27, 2015 at 08:54:34PM +0100, Robert Rosengren wrote:
> > Guenter and Jean,
> >
> > To sum up, my problems was related my kernel and hardware configuration, and it now works. Many thanks for your input!
> >
> > However, the values retrieved from hwmon sysfs is not the same as before the regmap patch. Guenter, the byte swap for the regval retrieved by regmap_read. In what order is the bits returned from that function, because it seems as if I disabled that code I get values as I expect (i.e. before the regmap patch).
> >
> Trying to understand. Are you saying everything works as expected
> if you keep byte_swap set to false ?
>
> That might well be, though it might mean that regmap has a bug
> in how it treats i2c word read operations. I'll have to look into it
> some more.

Remember that SMBus specifies that the LSB comes first (and i2c-core
implement things that way) while real I2C devices typically send the MSB
first. This has always caused confusion. This is why a lot of drivers
need byte-swapping.

--
Jean Delvare
SUSE L3 Support
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/