Re: [PATCH 3/4] ARM: dts: rockchip: add display nodes for rk322x

[Justin Swartz]

Hi Stephen,

On 2019-06-14 19:45, Stephen Boyd wrote:

> > diff --git a/arch/arm/boot/dts/rk322x.dtsi 
> > b/arch/arm/boot/dts/rk322x.dtsi
> > index da102fff96a2..148f9b5157ea 100644
> > --- a/arch/arm/boot/dts/rk322x.dtsi
> > +++ b/arch/arm/boot/dts/rk322x.dtsi
> > @@ -143,6 +143,11 @@
> > #clock-cells = <0>;
> > };
> >
> > +       display_subsystem: display-subsystem {
> > +               compatible = "rockchip,display-subsystem";
> > +               ports = <&vop_out>;
> > +       };
> > +
>
> What is this? It doesn't have a reg property so it looks like a virtual
> device. Why is it in DT?

This is a virtual device.

I assumed it would be acceptable to it find in a device tree due to 
binding documentation, 
"Documentation/devicetree/bindings/display/rockchip/rockchip-drm.txt, 
which states:

<quote>
The Rockchip DRM master device is a virtual device needed to list all
vop devices or other display interface nodes that comprise the
graphics subsystem.
</quote>

Without the "display_subsystem" device node, the HDMI PHY and 
rockchipdrmfb frame buffer device are not initialized.

Perhaps I should have included this in my commit message? :)

Regards
Justin