[PATCH 1/3] drm/exynos: add super device support

[Inki Dae]

2014-03-27 23:46 GMT+09:00 Philipp Zabel <p.zabel at pengutronix.de>:
> Hi Inki,
>
> Am Donnerstag, den 27.03.2014, 21:43 +0900 schrieb Inki Dae:
>> This patch adds super device support to bind sub drivers
>> using device tree.
>>
>> For this, you should add a super device node to each machine dt files
>> like belows,
>>
>> In case of using MIPI-DSI,
>>       exynos-drm {
>>               compatible = "samsung,exynos-drm";
>>               crtcs = <&fimd>;
>>               connectors = <&dsi>;
>>       };
>
> Russell had suggested a similar binding for i.MX, but we have since
> changed it to look like this instead:
>
> -       imx-drm {
> -               compatible = "fsl,imx-drm";
> -               crtcs = <&ipu 0>, <&ipu 1>;
> -               connectors = <&hdmi>, <&ldb>;
> -       };
> +       display-subsystem {
> +               compatible = "fsl,imx-display-subsystem";
> +               ports = <&ipu_di0>, <&ipu_di1>;

Is there any reason that ports property should have only crtc device
nodes?  I mean that if all device nodes for crtc and encoder/connector
devices are added to ports property, I think you could remove
imx_drm_components list and relevant codes.

I think this way we could use component framework and super device
node to resolve the probe order issue, and video interfaces nodes to
compose display pipelines.

Thanks,
Inki Dae

> +       };
>
> The ports are the two display output port nodes of the image processing
> unit (corresponding to a drm_crtc each), and the imx-drm driver that
> binds to the compatible value "fsl,imx-display-subsystem" automatically
> collects all encoders that hang off of those via the OF graph bindings
> (as documented in Documentation/devicetree/bindings/graph.txt in the
> staging tree). I don't know how well those bindings would fit on Exynos,
> maybe you could consider aligning your bindings with those.
>
> Either way, the generic term 'display-subsystem' is preferable to 'drm',
> as the latter is Linux specific, which the device tree bindings
> shouldn't be. The same goes for the 'crtcs' property. I'd prefer to
> avoid Linux specific legacy names in new device tree bindings.
>
> Also, since this adds new bindings, it should probably be sent to the
> devicetree mailing list and include some documentation.
>
> If you are interested in the previous discussion on the imx-drm
> supernode, here is the thread history:
>     "[PATCH v5 00/11] imx-drm dt bindings"
>     http://www.spinics.net/lists/arm-kernel/msg313112.html
>     "[PATCH v4 00/11] imx-drm dt bindings"
>     http://www.spinics.net/lists/dri-devel/msg54353.html
>     "[RFC PATCH v3 0/9] imx-drm dt bindings"
>     http://www.spinics.net/lists/arm-kernel/msg308529.html
>     "[RFC PATCH v2 0/4] imx-drm dt bindings"
>     http://www.spinics.net/lists/arm-kernel/msg306649.html
>     "[RFC PATCH 0/3] imx-drm dt bindings"
>     http://www.spinics.net/lists/arm-kernel/msg298290.html
>
> regards
> Philipp
>
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