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

[Patrick DELAUNAY]

Dear Marek,


> From: Marek Vasut <marex at denx.de>
> Sent: mercredi 1 avril 2020 01:48
> 
> Adjust the DDR configuration dtsi such that they only generate the DRAM
> configuration node, the DDR controller node is moved into the stm32mp157-u-
> boot.dtsi itself. This permits including multiple DDR configuration dtsi files in
> board DT.
> 
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
> Cc: Patrick Delaunay <patrick.delaunay at st.com>
> Cc: Patrice Chotard <patrice.chotard at st.com>
> ---
>  arch/arm/dts/stm32mp15-ddr.dtsi               | 357 +++++++++++-------
>  .../dts/stm32mp15-ddr3-1x4Gb-1066-binG.dtsi   |   1 +
>  .../dts/stm32mp15-ddr3-2x4Gb-1066-binG.dtsi   |   1 +
>  arch/arm/dts/stm32mp157-u-boot.dtsi           |  25 ++
>  4 files changed, 246 insertions(+), 138 deletions(-)
> 
> diff --git a/arch/arm/dts/stm32mp15-ddr.dtsi b/arch/arm/dts/stm32mp15-ddr.dtsi
> index 38f29bb789..50ca7092c4 100644
> --- a/arch/arm/dts/stm32mp15-ddr.dtsi
> +++ b/arch/arm/dts/stm32mp15-ddr.dtsi
> @@ -3,152 +3,233 @@
>   * Copyright : STMicroelectronics 2018
>   */
> 
> -/ {
> -	soc {
> -		ddr: ddr at 5a003000 {
> -			u-boot,dm-pre-reloc;

For information, binding file must be updated also
./doc/device-tree-bindings/memory-controllers/st,stm32mp1-ddr.txt

This binding and the helper file " stm32mp15-ddr.dtsi" is common with TF-A.

> +&ddr {
> +	config at DDR_MEM_LABEL {

I think that  "config at text"
don't respect the latest device tree rule and a warning is raised with latest dtc version

it is now mandatory to value after align @ with reg value

config@<reg> {
	reg = <reg>
}

It is why I prefer a name without meaning here (as config-1 / config-2), 
And selection is done on st,mem-name

config-1 {
....
}
config-2 {
....
}


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"
}


NB: I have a other idea, it is to use the "reg" as config identifier to select configuration, as it is done with OTP with "opp-supported-hw"
in linux/Documentation/devicetree/bindings/opp/opp.txt

And reg can be the identified with your GPIO setting

&ddr  {
	config at 2 {
		reg = 2;
#include "stm32mp15-ddr3-1x4Gb-1066-binG.dtsi"
	}
	config at 3 {
		reg = 3;
#include "stm32mp15-ddr3-2x4Gb-1066-binG.dtsi"
	}
}

This proposal avoids to compare a hardcoded string in SPL...

Regards

Patrick