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

[Rob Herring]

On Thu, Aug 25, 2016 at 7:03 AM, Jyri Sarha <jsarha at ti.com> wrote:
> Add "blue-and-red-crossed"-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. If the wires are crossed this boolean property
> should be present in the relevant devicetree node.
>
> The am335x-evm and am335x-evm have the blue and red wires crossed for
> 24 bit RGB mode and after this patch their LCDC nodes should have this
> property to get correct colors in the display.
>
> 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 at ti.com>
> ---
>  .../devicetree/bindings/display/tilcdc/tilcdc.txt  | 12 +++++++++++
>  drivers/gpu/drm/tilcdc/tilcdc_drv.c                | 24 ++++++++++++++++++++++
>  drivers/gpu/drm/tilcdc/tilcdc_drv.h                |  4 ++++
>  drivers/gpu/drm/tilcdc/tilcdc_plane.c              |  9 +++-----
>  4 files changed, 43 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt
> index 6efa4c5..48a660a 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-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?

>
>  Optional nodes:
>
> @@ -28,6 +30,14 @@ Optional nodes:
>     Documentation/devicetree/bindings/display/tilcdc/tfp410.txt for connecting
>     tfp410 DVI encoder or lcd panel to lcdc
>
> +[1] There is an errata about AM335x color wiring. For 16-bit color mode
> +    the wires work as they should (LCD_DATA[0:4] is for Blue[3:7]),
> +    but for 24 bit color modes the wiring of blue and red components is
> +    crossed and LCD_DATA[0:4] is for Red[3:7] and LCD_DATA[11:15] is
> +    for Blue[3-7]. For more details see section 3.1.1 in AM335x
> +    Silicon Errata:
> +    http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=sprz360
> +
>  Example:
>
>         fb: fb at 4830e000 {
> @@ -37,6 +47,8 @@ Example:
>                 interrupts = <36>;
>                 ti,hwmods = "lcdc";
>
> +               blue-and-red-wiring = "crossed";
> +

This needs to be updated.

Rob