Re: [PATCH 2/4] drm/tilcdc: Add blue-and-red-wiring -device tree property

[Rob Herring <robh@kernel.org>]

On Tue, Aug 16, 2016 at 12:24:28PM +0300, Jyri Sarha wrote:
> Add "blue-and-red-wiring"-device tree property and update devicetree
> binding document. The red and blue components are reversed between 24
> and 16 bit modes on am335x LCDC output pins. To get 24 RGB format the
> red and blue wires has to be crossed and this in turn causes 16 colors
> output to be in BGR format. With straight wiring the 16 color is RGB
> and 24 bit is BGR. The new property describes whether the red and blue
> wires are crossed or not. The am335x-evm has the wires going to LCD
> crossed and that is chosen to be the default mode if
> "blue-and-red-wiring"-property is not found.
> 
> For more details see section 3.1.1 in AM335x Silicon Errata:
> http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=sprz360
> 
> Signed-off-by: Jyri Sarha <jsarha@ti.com>
> ---
>  .../devicetree/bindings/display/tilcdc/tilcdc.txt  | 12 ++++++
>  drivers/gpu/drm/tilcdc/tilcdc_drv.c                | 44 ++++++++++++++++++++++
>  drivers/gpu/drm/tilcdc/tilcdc_drv.h                |  4 ++
>  drivers/gpu/drm/tilcdc/tilcdc_plane.c              |  9 ++---
>  4 files changed, 63 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt
> index 6efa4c5..992803b 100644
> --- 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-wiring: Either "crossed" or "straight", if not present
> +   crossed wiring is assumed for dtb backward compatibility. [1]

Just do a boolean and restrict it to a particular compatible string so 
we don't have to carry it forever on new parts.

Rob
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