[PATCH v5 2/2] arm64: dts: rockchip: add support for Radxa ROCK Pi E v3.0

[Dragan Simic]

On 2024-08-17 21:28, Dragan Simic wrote:
> Hello Fukaumi,
> 
> On 2024-08-17 00:20, FUKAUMI Naoki wrote:
>> On 8/17/24 07:11, Heiko Stübner wrote:
>>> Am Freitag, 16. August 2024, 23:34:29 CEST schrieb FUKAUMI Naoki:
>>>> Radxa ROCK Pi E v3.0 is a compact networking SBC[1] using the 
>>>> Rockchip
>>>> RK3328 chip that ships in a number of RAM/eMMC/WiFi/BT 
>>>> configurations:
>>>> 
>>>> - Rockchip RK3328 SoC
>>>> - Quad A53 CPU
>>>> - 512MB/1GB/2GB DDR4 RAM
>> (snip)
>>> can you please describe what is different in that v3 board?
>>> Describing what is different to require a separate board should've 
>>> been
>>> part of the commit message.
>>> 
>>> Because from those changes, the bottom line currently seems to be
>>> the same board with swapped mmc aliases?
>> 
>> it's new board which uses DDR4 RAM (instead of DDR3 RAM on Pi E).
>> different bootloader (U-Boot) is required.
>> 
>> adding v3 dts seems not to be so important for Linux, but it's very
>> important for U-Boot and OpenWrt(it includes bootloader for
>> distributed binary).
> 
> Aren't there different methods that allow such board variants to be
> supported in U-Boot, with no need for a separate DT in the kernel?
> IIRC, there are already more than a few examples of such board 
> variants,
> which require different DRAM initialization, which is covered in U-Boot
> by providing different builds that use the same DT.

As an example, please have a look at the following files in U-Boot:

- arch/arm/dts/rk3399-nanopi-m4-u-boot.dtsi
- arch/arm/dts/rk3399-nanopi-m4-2gb-u-boot.dtsi
- configs/nanopi-m4-rk3399_defconfig
- configs/nanopi-m4-2gb-rk3399_defconfig

Basically, there's no need for separate DTs in the kernel, just to 
support
board variants with different DRAM types in U-Boot.