Re: [PATCH] arm64: dts: rockchip: add dts for Radxa ROCK Pi E v3.0

[Dragan Simic <dsimic@manjaro.org>]

Hello Heiko,

On 2024-06-23 12:43, Heiko Stübner wrote:
> Am Sonntag, 23. Juni 2024, 10:18:58 CEST schrieb FUKAUMI Naoki:
>> On 6/23/24 17:07, Krzysztof Kozlowski wrote:
>> > On 23/06/2024 09:53, FUKAUMI Naoki wrote:
>> >> Radxa ROCK Pi E v3.0 has DDR4 SDRAM instead of DDR3 SDRAM.
>> >>
>> >> for Linux, this change doesn't make any difference from a device tree
>> >> POV. but, for bootloader (U-Boot TPL), it makes a difference.
>> >
>> > What difference?
>> 
>> U-Boot TPL initialize DDR SDRAM.
>> 
>> https://github.com/RadxaNaoki/u-boot/commit/16d823eb95fe311c82a8ebb31570b59b1c59c43b#diff-03ce6c241f5db74ae87d4d8654bfef5eeb5bc42a9f1ff3cc828b70b3b2ac51d2R4
>> https://github.com/RadxaNaoki/u-boot/commit/16d823eb95fe311c82a8ebb31570b59b1c59c43b#diff-31b80303774e7c10b527fb2dbc704b82e6c5ccdc6d53dd4f65861309ce0e7413R4
>> 
>> there is 1 letter difference, ddr"3" and ddr"4".
>> 
>> >> bootloader needs a separeted dts for v3, so I add new dts for it.
>> >> dtb can be shared between v3 and prior, so I don't touch Makefile.
>> >
>> > I don't understand. If you have the same DTB then you do not need second
>> > DTS.
>> 
>> 2nd dts is for bootloader. it's not needed for Linux.
> 
> but _what_ is this different dt needed for. If it is unchanged from the
> first one, why can't you reference that one in u-boot?
> 
> Similar to Krzysztof, I don't see _why_ you need a separate devicetree
> at all.

Please see the U-Boot patch submission [1] for more details.  Anyway,
I think in this case we'll need a rather full-fledged support for a new
board version, because that's what it actually is.

[1] 
https://lore.kernel.org/u-boot/20240623041542.50137-1-naoki@radxa.com/

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