RE: [PATCH v7 02/13] dt-bindings: display: renesas,rzg2l-du: Add support for RZ/G3E SoC

[Biju Das]

Hi Tommaso,

> -----Original Message-----
> From: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> Sent: 11 June 2026 13:43
> Subject: Re: [PATCH v7 02/13] dt-bindings: display: renesas,rzg2l-du: Add support for RZ/G3E SoC
> 
> Hi Rob,
> Thanks for your review.
> 
> On Wed, May 13, 2026 at 05:27:25PM -0500, Rob Herring wrote:
> > On Thu, May 07, 2026 at 11:21:30AM +0200, Tommaso Merciai wrote:
> > > The RZ/G3E SoC integrates two LCD controllers (LCDC0 and LCDC1),
> > > each containing a FCPVD, VSPD, and Display Unit (DU).
> > >
> > >  - LCDC0 supports DSI and LVDS (single or dual-channel) outputs.
> > >  - LCDC1 supports DSI, LVDS (single-channel), and RGB outputs.
> > >
> > > Add compatible string 'renesas,r9a09g047-du' and extend the binding
> > > to support two DU instances: add reg-names ('du0'/'du1'), extend
> > > reg, interrupts, and resets to maxItems: 2, and extend
> > > clocks/clock-names to six entries (aclk/pclk/vclk per instance, minItems: 3).
> >
> > Don't write what the diff has. I can read the diff for that.
> 
> Ouch, thanks.
> 
> >
> > >
> > > Drop the "Each port shall have a single endpoint." constraint since
> > > RZ/G3E ports expose multiple endpoints.
> > >
> > > Add a RZ/G3E-specific allOf rule mapping two DU instances to two ports:
> > >
> > >  - port@0 (DU0): endpoint@0 DSI, endpoint@2 LVDS ch0, endpoint@3
> > > LVDS ch1
> > >  - port@1 (DU1): endpoint@0 DSI, endpoint@1 RGB (DPAD), endpoint@3
> > > LVDS ch1
> > >
> > > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> > > ---
> > > v6->v7:
> > >  - Rebased on top of [1]
> > >    [1]
> > > https://lore.kernel.org/all/20260429170012.366537-1-prabhakar.mahade
> > > v-lad.rj@xxxxxxxxxxxxxx/
> > >  - Use single DRM device aggregating both DU instances (1 DU dt node),
> > >    modelling single port for each DU0, DU1 and multiple endpoints for
> > >    outputs.
> >
> > That seems like the completely wrong thing to do and you've given no
> > reason why you think it is the right choice.
> 
> 
> We had a discussion with Laurent at [1] about this topic.
> In particular:
> 
> DSI ip can select at runtime input data path or DU0 or DU1 via DSI_LINK_GPO0R VICH register. This can be
> done by managing the
> 2 DUs as single DRM device aggregating both DU instances that will spawn
> 2 crtcs. In this way at runtime we can select the output for DSI ip via the following commands:
> 
> modetest -M rzg2l-du -s 58@55:800x600-56.25@XR24 (DU0 -> DSI) modetest -M rzg2l-du -s 58@56:800x600-
> 56.25@XR24 (DU1 -> DSI)
> 
> This can be done using option [B] (single drm device that spawn 2 crtc).
> 
> Using option [A] we will have 2 drm devices 1 for DU0 and 1 for DU1 that each will spawn a single CRTC
> and the above feature will be not achievable.
> 
> In the end we need a way to have single DRM device that spawn 2 CRTCs.
> 
> A) Two device tree nodes rapresenting DU0 and DU1 design [v6]:
> 
> du0: display@16460000 {
> 	compatible = "renesas,r9a09g047-du";
> 	reg = <0 0x16460000 0 0x10000>;
> 	interrupts = <GIC_SPI 882 IRQ_TYPE_LEVEL_HIGH>;
> 	clocks = <&cpg CPG_MOD 0xed>,
> 			<&cpg CPG_MOD 0xee>,
> 			<&cpg CPG_MOD 0xef>;
> 	clock-names = "aclk", "pclk", "vclk";
> 	power-domains = <&cpg>;
> 	resets = <&cpg 0xdc>;
> 	renesas,vsps = <&vspd0 0>;
> 	status = "disabled";
> 
> 	ports {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		port@0 {
> 			reg = <0>;
> 			du0_out_dsi: endpoint {
> 			};
> 		};
> 
> 		port@2 {
> 			reg = <2>;
> 			du0_out_lvds0: endpoint {
> 			};
> 		};
> 
> 		port@3 {
> 			reg = <3>;
> 			du0_out_lvds1: endpoint {
> 			};
> 		};
> 	};
> };
> 
> du1: display@16490000 {
> 	compatible = "renesas,r9a09g047-du";
> 	reg = <0 0x16490000 0 0x10000>;
> 	interrupts = <GIC_SPI 922 IRQ_TYPE_LEVEL_HIGH>;
> 	clocks = <&cpg CPG_MOD 0x1a8>,
> 			<&cpg CPG_MOD 0x1a9>,
> 			<&cpg CPG_MOD 0x1aa>;
> 	clock-names = "aclk", "pclk", "vclk";
> 	power-domains = <&cpg>;
> 	resets = <&cpg 0x11e>;
> 	renesas,vsps = <&vspd1 0>;
> 	status = "disabled";
> 
> 	ports {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		port@0 {
> 			reg = <0>;
> 			du1_out_dsi: endpoint {
> 			};
> 		};
> 
> 		port@1 {
> 			reg = <1>;
> 			du1_out_rgb: endpoint {
> 			};
> 		};
> 
> 		port@3 {
> 			reg = <3>;
> 			du1_out_lvds1: endpoint {
> 			};
> 		};
> 	};
> };
> 
> ---
> 
> B) Single device tree node design aggregating both DU instances [v7]:
> 
> du: display@16460000 {
> 	compatible = "renesas,r9a09g047-du";
> 	reg = <0 0x16460000 0 0x10000>,
> 		<0 0x16490000 0 0x10000>;
> 	reg-names = "du0", "du1";
> 	interrupts = <GIC_SPI 882 IRQ_TYPE_LEVEL_HIGH>,
> 			<GIC_SPI 922 IRQ_TYPE_LEVEL_HIGH>;
> 	clocks = <&cpg CPG_MOD 0xed>,
> 			<&cpg CPG_MOD 0xee>,
> 			<&cpg CPG_MOD 0xef>,
> 			<&cpg CPG_MOD 0x1a8>,
> 			<&cpg CPG_MOD 0x1a9>,
> 			<&cpg CPG_MOD 0x1aa>;
> 	clock-names = "aclk", "pclk", "vclk",
> 			"aclk1", "pclk1", "vclk1";
> 	power-domains = <&cpg>;
> 	resets = <&cpg 0xdc>, <&cpg 0x11e>;
> 	reset-names = "resetn", "resetn1";
> 	renesas,vsps = <&vspd0 0>, <&vspd1 0>;
> 	status = "disabled";
> 
> 	ports {
> 		#address-cells = <1>;
> 		#size-cells = <0>;
> 
> 		port@0 {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 
> 			reg = <0>;
> 
> 			du0_out_dsi: endpoint@0 {
> 				reg = <0>;
> 			};
> 
> 			du0_out_lvds0: endpoint@2 {
> 				reg = <2>;
> 			};
> 
> 			du0_out_lvds1: endpoint@3 {
> 				reg = <3>;
> 			};
> 		};
> 
> 		port@1 {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 
> 			reg = <1>;
> 
> 			du1_out_dsi: endpoint@0 {
> 				reg = <0>;
> 			};
> 
> 			du1_out_rgb: endpoint@1 {
> 				reg = <1>;
> 			};
> 
> 			du1_out_lvds1: endpoint@3 {
> 				reg = <3>;
> 			};
> 		};
> 	};
> };
> 
> ---
> 
> Please Biju, Laurent correct me if I'm missing something.
> 
> [1] https://patchwork.kernel.org/project/linux-renesas-
> soc/patch/8f814f22ff62dcde6153260e2c8c29a5415c9a89.1775636898.git.tommaso.merciai.xr@xxxxxxxxxxxxxx/
> [v6] https://patchwork.kernel.org/project/linux-renesas-
> soc/patch/8f814f22ff62dcde6153260e2c8c29a5415c9a89.1775636898.git.tommaso.merciai.xr@xxxxxxxxxxxxxx/
> [v7] https://patchwork.kernel.org/project/linux-renesas-
> soc/patch/ff8e401a0667970a42a55420dcb071e34730a923.1778141145.git.tommaso.merciai.xr@xxxxxxxxxxxxxx/
> 

RZ/G3E LVDS support single link (2ch): extended display and single link (multi) mirror display
I believe to support this feature you need single node solution.

Not sure, you just need to extend like R-Car with 1 ports containing all the 4 ports
Maybe You could try this as well??

Or

1 Ports containing 2 port that contains 3 endpoints each (Current patch)

Cheers,
Biju