Re: [PATCH 0/4] lis3lv02d: update DT binding for use with Nokia N900

On Fri, Dec 13, 2013 at 11:31:39PM +0100, Éric Piel wrote:

On 13-12-13 21:54, Sebastian Reichel wrote:

quoted

The lis302 has already a DT binding described in [0],
which descibes misc. hardware properties. The current
binding does not support all values needed to convert
the Nokia N900's platform data to DT.

This patchset introduces support for describing inverted
axis, configuration of second wakeup unit and wakeup
threshold support.

All the three patches related to the lis3lv02d driver look fine to me.
Here is my signed-off for patches 2, 3, and 4:
Signed-off-by: Éric Piel <redacted>

I've got 2 side questions:
 * How do you write a negative value in a DTS file? Is this just the
very standard way (i.e., -), or do you need to use a specific
technique (such as 2-completemnt on 32 bits)? If it's not the
standard way, it should probably be documented somewhere.

One can simply use -, but one has to put the value into (). This is
because DT supports simple mathematical operations for the values,
e.g. 5-10 and must have some way to distinguish between (5) (-10)
and (5-10).

Here is an example for N900 axis configuration from DT file:

 st,axis-x = <1>;    /* LIS3_DEV_X */
 st,axis-y = <(-2)>; /* LIS3_INV_DEV_Y */
 st,axis-z = <(-3)>; /* LIS3_INV_DEV_Z */

I had some trouble to find this out myself, so probably its a good
idea to document this somewhere.

 * Who wants to carry these patches? Can they all go via the
devicetree branch? Or maybe Arnd or Greg would prefer to pick them
via the misc driver branch? Both ways are fine for me...

I don't care, but it would be nice to see this in 3.14.

-- Sebastian