Re: [PATCH v1 00/12] drm/rockchip: RK356x VOP2 support

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Nov 17, 2021 at 08:54:37AM -0600, Rob Herring wrote:
> On Wed, Nov 17, 2021 at 8:34 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >
> > This series adds initial graphics support for the Rockchip RK356[68]
> > SoCs.  Graphics support is based around the VOP2 controller which
> > replaces the VOP controller found on earlier Rockchip SoCs. The driver
> > has been tested with HDMI support included in this series and MIPI-DSI
> > which is not included because it needs some more work. The driver is
> > taken from the downstream Rockchip kernel and heavily polished, most non
> > standard features have been removed for now. I tested the driver with
> > the libdrm modetest utility and also with weston with both pixman and
> > panfrost driver support. Michael Riesch reported the driver to work on
> > the RK3566 as well, but device tree support for this SoC is not yet
> > included in this series.
> 
> Can you outline what exactly you want to disable? I don't think
> 'status' is the right way. I think between the parent device being
> disabled, an incomplete graph and user configuration choice that
> should be enough to disable parts.

The VOP2 on the RK3568 has three CRTCS, or video ports (VP) in Rockchip
nomenclature. Each of them can be connected to the different outputs,
like HDMI, MIPI-DSI and so on. In the device tree the CRTCs are
described as of-graph ports with links to the HDMI, MIPI-DSI nodes.
An example limited to HDMI looks like this:

	vop: vop@fe040000 {
		compatible = "rockchip,rk3568-vop";
		vop_out: ports {
			vp0: port@0 {
				vp0_out_hdmi: endpoint@0 {
					reg = <0>;
					remote-endpoint = <&hdmi_in_vp0>;
					status = "disabled";
				};

				... MIPI, dP, ...
			};

			vp1: port@1 {
				vp1_out_hdmi: endpoint@0 {
					reg = <0>;
					remote-endpoint = <&hdmi_in_vp1>;
					status = "disabled";
				};

				... MIPI, dP, ...
			};

			vp2: port@2 {
				...
			};
		};
	};

	hdmi: hdmi@fe0a0000 {
		compatible = "rockchip,rk3568-dw-hdmi";
		ports {
			hdmi_in: port@0 {
				hdmi_in_vp0: endpoint@0 {
					reg = <0>;
					remote-endpoint = <&vp0_out_hdmi>;
					status = "disabled";
				};

				hdmi_in_vp1: endpoint@1 {
					reg = <1>;
					remote-endpoint = <&vp1_out_hdmi>;
					status = "disabled";
				};

				...
			};
		};
	};

Theoretically every VP can be routed to every output, but depending on
the board there are some constraints. For example for the three vps
there are only two PLLs for the pixel clock, and the HDMI port is
hardwired to one single PLL. To avoid different VPs setting conflicting
rates on a PLL we can only allow a subset of the possible routes.

Sascha

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