[PATCH 3/4] [RFC] ARM: dts: stm32: Rework DDR DT inclusion

[Patrick DELAUNAY]

Hi Marek,

> From: Marek Vasut <marex at denx.de>
> Sent: mercredi 8 avril 2020 15:54
> 
> On 4/8/20 12:09 PM, Patrick DELAUNAY wrote:
> > Hi,
> 
> Hi,
> 
> >> From: Marek Vasut <marex at denx.de>
> >> Sent: mardi 7 avril 2020 22:01
> >>
> >> On 4/7/20 3:00 PM, Patrick DELAUNAY wrote:
> >>> Dear Marek,
> >>
> >> Hi,
> >>

[...]

> >>>
> >>> And I want to propose, for DH board with several configuration
> >>>
> >>> &ddr  {
> >>> 	config-1 {
> >>> #include "stm32mp15-ddr3-1x4Gb-1066-binG.dtsi"
> >>> 	}
> >>> 	config-2 {
> >>> #include "stm32mp15-ddr3-2x4Gb-1066-binG.dtsi"
> >>> 	}
> >>> }
> >>>
> >>>
> >>> For ST board with only one configuration (don't change the device
> >>> tree, config at the same level) &ddr  { #include
> >>> "stm32mp15-ddr3-1x4Gb-1066-binG.dtsi"
> >>> }
> >>>
> >>>

[...]

> >>
> >> I would much rather prefer to avoid manually writing the config@<foo>
> >> parts, that should be handled by some macro magic instead. With my
> >> proposal, it is not necessary at all either.
> >

[....]

> >
> > So the file generate by CubeMX don't change =  stm32mp15-ddr3-1x4Gb-1066-
> binG.dtsi and stm32mp15-ddr3-2x4Gb-1066-binG.dtsi.
> >
> > The ST board devicetree don't change: the DDR configuration is still
> > in ddr node (as in TF-A)
> >
> > For your board, the device tree
> > /arch/arm/dts/stm32mp15xx-dhcor-u-boot.dtsi
> >
> > [...]
> > #define DDR_MEM_CONFIG 2
> > #include "stm32mp15-ddr3-1x4Gb-1066-binG.dtsi"
> >
> > #define DDR_MEM_CONFIG 3
> > #include "stm32mp15-ddr3-2x4Gb-1066-binG.dtsi"
> > [...]
> >
> > And you can directly compare reg value of sub node with ddr3code.
> >
> > It is more acceptable ?
> 
> I wonder, can't we have some sort of macro where you would specify a compatible
> string for the DDR config (on which you can match in your
> board_stm32mp1_ddr_config_name_match() and the dtsi file to be included, and
> the macro would generate the necessary entries in the &ddr {} controller node ?
> 
> E.g. like this:
> 
> #include "stm32mp15-ddr.dtsi"
> STM32MP15_DDR("vendor,board-1gib", stm32mp15-ddr3-2x4Gb-1066-binG.dtsi);
> STM32MP15_DDR("vendor,board-2gib", stm32mp15-ddr3-4x4Gb-1066-binG.dtsi);
> 
> and then in board_stm32mp1_ddr_config_name_match()
> {
>  if (!strcmp(..., "vendor,board-1gib"))
>     return 0;
>  ...
> }

Yes, I agree, compatible is the better solution and the binding 

./doc/device-tree-bindings/memory-controllers/st,stm32mp1-ddr.txt becomes

ddr: ddr at 0x5A003000{
	compatible = "st,stm32mp1-ddr";
	[...]

	config-1 {
		compatible = "vendor,board-1gib";

		st,mem-name = "..."
		[...]
		st,phy-timing = <...>
	}
	config-2 {
		compatible = "vendor,board-2gib";
		st,mem-name = "..."
		[...]
		st,phy-timing = <...>
	}
	status = "okay";
}

And you match this configuration with compatible.

For the macro, it should be perfect, if it is not too complicate.

Because I afraid that "#include" in macro isn't allowed.

regards

Patrick