On Sat, Oct 3, 2015 at 6:11 PM, Robert Jarzmik <robert.jarzmik@xxxxxxx> wrote:
> Add documentation for the PXA frambuffer devicetree binding.
>
> Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
> Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx>
> Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> Cc: linux-fbdev@xxxxxxxxxxxxxxx
>
> ---
> .../devicetree/bindings/video/marvell,pxafb.txt | 75 ++++++++++++++++++++++
> 1 file changed, 75 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/video/marvell,pxafb.txt
>
> diff --git a/Documentation/devicetree/bindings/video/marvell,pxafb.txt b/Documentation/devicetree/bindings/video/marvell,pxafb.txt
> new file mode 100644
> index 000000000000..489055bf3c57
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/marvell,pxafb.txt
> @@ -0,0 +1,75 @@
> +PXA LCDC Framebuffer
> +-----------------------------------------------------
> +
> +Required properties:
> +- compatible :
> + "marvell,pxa2xx-fb",
Should be "marvell,pxa2xx-lcd-controller", "marvell,pxa2xx-lcdc" or
something like this.
> +- reg : Should contain 1 register ranges(address and length).
> + Can contain an additional register range(address and length)
> + for fixed framebuffer memory. Useful for dedicated memories.
> +- interrupts : framebuffer controller interrupt
> +- display: a phandle pointing to the display node
> +
> +Required nodes:
> +- display: a display node is required to initialize the lcd panel
> + This should be in the board dts.
I'd prefer to use an of-graph link to a panel node with a proper
compatible value for the panel, instead of this custom display
property.
That way, if somebody ever decides convert the fbdev driver to a drm
driver, we don't have to change the device tree and can directly use
drm_panel.
> +- default-mode: a videomode within the display with timing parameters
> + as specified below.
> +- bits-per-pixel: pixel data bus width of the LCD panel
Would bus-width be better here?
> +Optional properties:
> +- lcd-supply: Regulator for LCD supply voltage.
How does this differ from the regulator below?
> +- enable-transparency-bit: if framebuffer colorspace reserves a bit for
> + transparency
That doesn't belong in the device tree.
> +- enable-greyscale-cmap: true if palette is a grayscale based instead of color
I suspect this doesn't belong in the device tree either. Does this
specify the pixel format of the memory framebuffer?
> +Example:
> +
> + fb0: video@0x44000000 {
> + compatible = "marvell,pxa2xx-fb";
> + reg = <0x44000000 0x10000>;
> + interrupts = <17>;
> + clocks = <&clks CLK_LCD>;
> + interrupts = <23>;
> + display = <&display0>;
> + status = "okay";
> +
> + enable-transparency-bit = <0>;
> + enable-greyscale-cmap = <0>;
> + #address-cells = <1>;
> + #size-cells = <1>;
What are the #address/size-cells needed for?
> + };
> +
> +PXA LCDC Display
> +-----------------------------------------------------
> +Required properties (as per of_videomode_helper):
> + - lcd-type: either "mono-stn", "mono-dstn", "color-stn", "color-dstn",
> + "color-tft", "smart-panel"
> + - bits-per-pixel: LCD data bus width
This is already found in the lcd controller node above.
> +Optional properties (as per of_videomode_helper):
> + - power-regulator: power supply regulator to the LCD to power it on or off
regards
Philipp
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