Re: [PATCH] sunxi: board: provide CPU idle states to loaded OS

[Andrey Skvortsov <andrej.skvortzov@gmail.com>]

Hi Andrey,

On 23-09-05 09:27, Andre Przywara wrote:
> On Mon,  4 Sep 2023 23:54:30 +0300
> Andrey Skvortsov <andrej.skvortzov@gmail.com> wrote:
> 
> Hi Andrey,
> 
> > When using SCPI as the PSCI backend, firmware can wake up the CPUs and
> > cluster from sleep, so CPU idle states are available for loaded OS to
> > use. TF-A modifies DTB to advertise available CPU idle states, when
> > SCPI is detected. This change copies nodes added by TF-A to any new
> > dtb that is used for loaded OS.
> 
> Why do you need that, exactly? Why not just use $fdtcontroladdr for the
> kernel? We now keep the U-Boot copy of the .dts files in sync with the
> kernel. If you need to modify the DT in U-Boot, for instance by applying
> overlays, you can copy that DTB into a better suitable location first:
> => fdt move $fdtcontroladdr $fdt_addr_r
> 
> In any case, there shall be only one DT, that one in the U-Boot image. Why
> do you need to load another one for the kernel?

extlinux is used by distributions (sometimes with device-specific changes especially
for platforms not fully supported by mainline yet), then U-Boot loads DT defined in
extlinux.conf file. u-boot scripts are not used in case of extlinux at all.

-- 
Best regards,
Andrey Skvortsov