Subject: Re: [PATCH 2/4] Revert "dt-bindings: display: bridge: ldb: Fill in reg property"

From: Rob Herring <[email-masked]>
Date: Mon, 1 Jun 2026 17:29:41 -0500

On Wed, May 13, 2026 at 12:26:40PM +0200, Marco Felsch wrote:
> On 26-05-07, Rob Herring wrote:
> > On Thu, May 7, 2026 at 6:55 AM Marco Felsch <[email-masked]> wrote:
> 
> ...
> 
> > > > But nowhere have you said the LDB registers are mixed with other
> > > > functions. If they aren't, then there is absolutely nothing to change
> > > > in the binding. If they are, then yes, we shouldn't have 'reg'.
> > >
> > > No they aren't mixed with other functions (for now).
> > 
> > For now? Is the h/w going to change or is the binding *still* incomplete.
> 
> Sorry for the confusion. By for now I mean that NXP tend to reuse IPs
> but with minor changes. So no, the binding is not incomplete with our
> current HW knowledge.

If such changes occur, then we can deal with it at that time.

> > > Can you please
> > > confirm that mixing 'reg' based sub-device nodes with non 'reg' based
> > > sub-device nodes  is allowed? E.g. if the below example is allowed?
> > >
> > >         system-controller@4ac10000 {
> > >                 compatible = "fsl,imx93-media-blk-ctrl", "syscon";
> > >                 reg = <0x4ac10000 0x10000>;
> > >                 #address-cells = <1>;
> > >                 #size-cells = <1>;
> > >
> > >                 ...
> > >
> > >                 bridge@5c {
> > >                         compatible = "fsl,imx8mp-ldb";
> > >                         reg = <0x5c 0x4>, <0x128 0x4>;
> > >                         reg-names = "ldb", "lvds";
> > >
> > >                         ...
> > >                 };
> > >
> > >                 dpi-bridge {
> > >                         compatible = "nxp,imx93-pdfc";
> > >
> > >                         ...
> > 
> > Depends what is in "...". If only a compatible, then no. If there are
> > actual resources defined, then yes.
> 
> Please see the below full example, is this allowed?
> 
> system-controller@4ac10000 {
> 	compatible = "fsl,imx93-media-blk-ctrl", "syscon";
> 	reg = <0x4ac10000 0x10000>;
> 	#address-cells = <1>;
> 	#size-cells = <1>;
> 
> 	...
> 
> 	bridge@5c {
> 		compatible = "fsl,imx8mp-ldb";
> 		reg = <0x5c 0x4>, <0x128 0x4>;
> 		reg-names = "ldb", "lvds";
> 		clocks = <&clk IMX8MP_CLK_MEDIA_LDB_ROOT>;
> 		clock-names = "ldb";
> 		assigned-clocks = <&clk IMX8MP_CLK_MEDIA_LDB>;
> 		assigned-clock-parents = <&clk IMX8MP_VIDEO_PLL1_OUT>;
> 		status = "disabled";
> 
> 		ports {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 
> 			port@0 {
> 				reg = <0>;
> 
> 				ldb_from_lcdif2: endpoint {
> 					remote-endpoint = <&lcdif2_to_ldb>;
> 				};
> 			};
> 
> 			port@1 {
> 				reg = <1>;
> 
> 				ldb_lvds_ch0: endpoint {
> 				};
> 			};
> 
> 			port@2 {
> 				reg = <2>;
> 
> 				ldb_lvds_ch1: endpoint {
> 				};
> 			};
> 		};
> 	};
> 
> 	dpi-bridge {
> 		compatible = "nxp,imx93-pdfc";
> 		status = "disabled";
> 
> 		ports {
> 			#address-cells = <1>;
> 			#size-cells = <0>;
> 
> 			port@0 {
> 				reg = <0>;
> 
> 				dpi_from_lcdif: endpoint {
> 					remote-endpoint = <&lcdif_to_dpi>;
> 				};
> 			};
> 
> 			port@1 {
> 				reg = <1>;
> 
> 				dpi_to_panel: endpoint {
> 				};
> 			};
> 		};
> 	};
> };

Yes, this seems fine.

Rob