Re: [PATCH v2 4/4] video: mmp: add device tree support

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On 14/01/14 13:16, Zhou Zhu wrote:
> add device tree support for mmp fb/controller
> the description of DT config is at
> Documentation/devicetree/bindings/fb/mmp-disp.txt
> 
> Signed-off-by: Zhou Zhu <zzhu3@marvell.com>
> ---
>  Documentation/devicetree/bindings/fb/mmp-disp.txt |   60 ++++++++
>  drivers/video/mmp/fb/mmpfb.c                      |   73 ++++++----
>  drivers/video/mmp/hw/mmp_ctrl.c                   |  160 ++++++++++++++++-----
>  3 files changed, 235 insertions(+), 58 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/fb/mmp-disp.txt
> 
> diff --git a/Documentation/devicetree/bindings/fb/mmp-disp.txt b/Documentation/devicetree/bindings/fb/mmp-disp.txt
> new file mode 100644
> index 0000000..80702f5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/fb/mmp-disp.txt
> @@ -0,0 +1,60 @@
> +* Marvell MMP Display (MMP_DISP)
> +
> +To config mmp display, 3 parts are required to be set in dts:
> +1. mmp fb
> +Required properties:
> +- compatible: Should be "marvell,<soc>-fb".
> +- marvell,path: Should be the path this fb connecting to.
> +- marvell,overlay-id: Should be the id of overlay this fb is on.
> +- marvell,dmafetch-id: Should be the dma fetch id this fb using.
> +- marvell,default-pixfmt: Should be the default pixel format when this fb is
> +turned on.
> +
> +2. mmp controller
> +Required properties:
> +- compatible: Should be "marvell,<soc>-disp".
> +- reg: Should be address and length of the register set for this controller.
> +- interrupts: Should be interrupt of this controller.
> +
> +Required sub-node:
> +- path:
> +Required properties in this sub-node:
> +-- marvell,overlay_num: Should be number of overlay this path has.

If that one tells how many overlays there are, maybe "num_overlays"
would be better.

> +-- marvell,output-type: Should be output-type settings
> +-- marvell,path-config: Should be path-config settings
> +-- marvell,link-config: Should be link-config settings
> +-- marvell,rbswap: Should be rbswap settings

If these terms (output-type, path-config, ...) are straight from the HW
manual, then fine. But if they are not clear, or are driver specific,
the values these can have should be documented here.

> +
> +3. panel
> +Required properties:
> +- marvell,path: Should be path that this panel connected to.
> +- other properties each panel has.
> +
> +Examples:
> +
> +fb: mmp-fb {
> +	compatible = "marvell,pxa988-fb";
> +	marvell,path = <&path1>;
> +	marvell,overlay-id = <0>;
> +	marvell,dmafetch-id = <1>;
> +	marvell,default-pixfmt = <0x108>;
> +};
> +
> +disp: mmp-disp@d420b000 {
> +	compatible = "marvell,pxa988-disp";
> +	reg = <0xd420b000 0x1fc>;
> +	interrupts = <0 41 0x4>;
> +	path1: mmp-pnpath {
> +		marvell,overlay-num = <2>;
> +		marvell,output-type = <0>;
> +		marvell,path-config = <0x20000000>;
> +		marvell,link-config = <0x60000001>;
> +		marvell,rbswap = <0>;
> +	};
> +};
> +
> +panel: <panel-name> {

How is the panel linked to all this? The nodes above do not refer to the
panel.

> +	...
> +	marvell,path = <&path1>;
> +	...
> +};

It's a bit difficult to say much about this, as I have no knowledge
about mmp.

But I don't quite understand what the pxa988-fb is. Is that some kind of
virtual device, only used to set up fbdev side? And pxa988-disp is the
actual hardware device?

If so, I don't really think pxa988-fb should exist in the DT data at
all, as it's not a hardware device.

Why isn't there just one node for pxa988-disp, which would contain all
the above information?

 Tomi



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