Re: [PATCH 1/3] spi: Add a spi_w8r16be() helper

[Guenter Roeck]

On Fri, Sep 27, 2013 at 08:22:33PM +0100, Mark Brown wrote:
> On Fri, Sep 27, 2013 at 08:46:56PM +0200, Lars-Peter Clausen wrote:
> 
> > According to the documentation of spi_w8r16() it is a feature.
> 
> > 	* The number is returned in wire-order, which is at least sometimes
> >  	* big-endian.
> 
> Indeed.  I don't think that's terribly well thought through though,
> especially not now we have annotations for endianness (as you noticed!).
> 
> > There seem to be at least two users though which assume that the result is
> > in native endianness drivers/hwmon/ads7871.c and drivers/mfd/stmpe-spi.c
> 
> Yeah, I saw.  The ads7871 is just going to break when run on the
> opposite endianness to the one it was (hopefully) tested on since it
> doesn't make any effort I saw to cope with endianness.  Looking at the
> history it's not terribly obvious which that was but it'd be surprising
> to see a little endian register...
> 
It might make sense to convert the ads7871 driver to an iio driver;
it doesn't look like the chip is commonly used for hardware monitoring.

At least if someone finds the time to do it ;).

Guenter
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