RE: [EXT] Re: [PATCH v1] arm64: dts: fsl: ls1028a-rdb: Add dts file to choose swp5 as dsa master

[Hongbo Wang]

> On Mon, Aug 16, 2021 at 06:03:52AM +0000, Hongbo Wang wrote:
> > > I was going to suggest as an alternative to define a device tree
> > > overlay file with the changes in the CPU port assignment, instead of
> > > defining a wholly new DTS for the LS1028A reference design board.
> > > But I am pretty sure that it is not possible to specify a
> > > /delete-property/ inside a device tree overlay file, so that won't actually
> work.
> >
> > hi Vladimir,
> >
> >   if don't specify "/delete-property/" in this dts file, the
> > corresponding dtb will not work well, so I add it to delete 'ethernet' property
> from mscc_felix_port4 explicitly.
> 
> Judging by the reply, I am not actually sure you've understood what has been
> said.
> 
> I said:
> 
> There is an option to create a device tree overlay:
> 
> https://www.kernel.org/doc/html/latest/devicetree/overlay-notes.html
> 
> We use these for the riser cards on the LS1028A-QDS boards.
> 
> https://source.codeaurora.org/external/qoriq/qoriq-components/linux/tree/ar
> ch/arm64/boot/dts/freescale/fsl-ls1028a-qds-13bb.dts?h=LSDK-20.12-V5.4
> 
> They are included as usual in a U-Boot ITB file:
> 
> / {
> 	images {
> 		/* Base DTB */
> 		ls1028aqds-dtb {
> 			description = "ls1028aqds-dtb";
> 			data =
> /incbin/("arch/arm64/boot/dts/freescale/fsl-ls1028a-qds.dtb");
> 			type = "flat_dt";
> 			arch = "arm64";
> 			os = "linux";
> 			compression = "none";
> 			load = <0x90000000>;
> 			hash@1 {
> 				algo = "crc32";
> 			};
> 		};
> 		/* Overlay */
> 		fdt@ls1028aqds-13bb {
> 			description = "ls1028aqds-13bb";
> 			data =
> /incbin/("arch/arm64/boot/dts/freescale/fsl-ls1028a-qds-13bb.dtb");
> 			type = "flat_dt";
> 			arch = "arm64";
> 			load = <0x90010000>;
> 		};
> 	};
> };
> 
> In U-Boot, you apply the overlay as following:
> 
> tftp $kernel_addr_r boot.itb && bootm
> $kernel_addr_r#ls1028aqds#ls1028aqds-13bb
> 
> It would have been nice to have a similar device tree overlay that changes the
> DSA master from eno2 to eno3, and for that overlay to be able to be applied
> (or not) from U-Boot.
> 
> But it's _not_ possible, because you cannot put the /delete-property/ (that you
> need to have) in the .dtbo file. Or if you put it, it will not delete the property
> from the base dtb.
> 
> That's all I said.

thanks for the detailed explanation,
I have got your point.

thanks,
hongbo