[PATCH v2 2/7] drm/tilcdc: Add blue-and-red-crossed devicetree property

[Jyri Sarha]

On 08/26/16 15:51, Rob Herring wrote:
>> --- a/Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt
>> > +++ b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt
>> > @@ -17,6 +17,8 @@ Optional properties:
>> >     the lcd controller.
>> >   - max-pixelclock: The maximum pixel clock that can be supported
>> >     by the lcd controller in KHz.
>> > + - blue-and-red-crossed: Boolean property, set this of blue and red wires
>> > +   for LCD_DATA are crossed for 24-bit RGB support (and 16-bit BGR mode). [1]
> Doesn't this need to be blue-and-red-straight for compatibility?
> 

There is no way to be backward compatible with all am3 based devices.
This choice keeps the compatibility with Beaglebone-Black as far as it
can be kept and it is more logical choice for the binding. After all BBB
is way more common device than am335x-evm and am335x-evmsk are together.

I don't think there is any problems with the boards that have dts file
in the mainline source tree, like these three boards, as if the user
uses the latest mainline kernel, he probably uses the latest dtb file too.

The problem is the custom boards with custom dts files. I can not think
of any way to deal with this problem while still being 100% compatible
with all the dtb out there. This default setting is compatible with
standard colour wiring that does not take the colour errata into account.

BR,
Jyri