Re: [PATCH v2] video: fbdev: add Marvell PXA framebuffer binding

From: Rob Herring
Date: Tue Oct 06 2015 - 09:30:54 EST


On Sun, Oct 4, 2015 at 5:31 AM, Robert Jarzmik <robert.jarzmik@xxxxxxx> wrote:
> Add documentation for the PXA frambuffer devicetree binding.

Strictly speaking this is a binding for PXA display controller, not a
Linux FB driver. There are lots of "framebuffer" and "DRM" bindings
which I'm trying to curb.

> Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
> ---
> Since v1: Philipp's review on the whole binding
> ---
> .../devicetree/bindings/video/marvell,pxafb.txt | 80 ++++++++++++++++++++++

Please put in bindings/display/ as I'm consolidating all the display
related bindings there[1].

> 1 file changed, 80 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..4d6bd490680d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/marvell,pxafb.txt
> @@ -0,0 +1,80 @@
> +PXA LCDC Framebuffer
> +--------------------
> +
> +Required properties:
> + - compatible :
> + "marvell,pxa2xx-lcdc",

No differences in h/w for any of the chips?

> + - 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.

This is memory that can't be used for anything else? We already have
reserved-memory for this if it is just RAM. There's also a binding for
on-chip SRAM which should probably be used if the memory is usable for
other things.

> + - interrupts : framebuffer controller interrupt
> +
> +Required nodes:
> + - clocks: phandle to input clocks.
> + - port: connection to the LCD panel (see video-interfaces.txt)
> + This nodes must have its properties bus-width and remote-endpoint set.
> + This should be in the board dts.
> +
> +Example:
> +
> + lcd-controller@40500000 {
> + compatible = "marvell,pxa2xx-lcdc";
> + reg = <0x44000000 0x10000>;
> + interrupts = <17>;
> + clocks = <&clks CLK_LCD>;
> + interrupts = <23>;
> + status = "okay";
> +
> + port {
> + lcdc_out: endpoint {
> + remote-endpoint = <&panel_in>;
> + bus-width = <16>;
> + };
> + };
> + };
> +
> +PXA LCDC Display

This should not be specific to PXA, but for this panel. This should be
in bindings/display/panel/.

> +----------------
> +Required properties (as per of_videomode_helper):
> + - lcd-type: either "mono-stn", "mono-dstn", "color-stn", "color-dstn",
> + "color-tft", "smart-panel"
> +
> +Optional properties (as per of_videomode_helper):
> + - power-supply: power supply regulator to the LCD to power it on or off
> + (see regulator.txt)
> + - backlight: backlight control (see backlight.txt)
> +
> +Required nodes:
> + - port: connection to the LCD controller
> + - display-timings: panel timings (see display-timing.txt)

If lcd-type is smart-panel, then this node would not make sense.

> +
> +Example:
> + panel {
> + compatible = "toshiba,ltm0305a776";
> + lcd-type = "color-tft";
> +
> + power-supply = <&lcd_supply>;
> + backlight = <&lcd_backlight>;
> +
> + port {
> + panel_in: endpoint {
> + remote-endpoint = <&lcdc_out>;
> + };
> + };
> +
> + display-timings {
> + native-mode = <&timing0>;
> + timing0: 240p {
> + /* 240x320p24 */
> + clock-frequency = <4545000>;
> + hactive = <240>;
> + vactive = <320>;
> + hfront-porch = <4>;
> + hback-porch = <6>;
> + hsync-len = <4>;
> + vback-porch = <5>;
> + vfront-porch = <3>;
> + vsync-len = <2>;
> + };
> + };
> + };
> --
> 2.1.4
>

[1] https://lkml.org/lkml/2015/10/1/899
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