[U-Boot] [PATCH] clk: sifive: Fix ethernet regression on HiFive Unleashed

[Bin Meng]

Hi Marcus,

On Sun, Sep 8, 2019 at 9:19 PM Marcus Comstedt <marcus at mc.pp.se> wrote:
>
>
> Bin Meng <bmeng.cn at gmail.com> writes:
>
> > OpenSBI v0.4 works fine if you supply the the Linux DTB via
> > FW_PAYLOAD_FDT_PATH when building OpenSBI.
>
> And which "Linux DTB" should that be?  Since RISC-V seems to be going

The one in arch/riscv/boot/dts/sifive.

> the same annoying way as ARM with a requirement that you switch DTB
> every time you switch kernel version even though the hardware the DTB
> describes stays the same, because the syntax of the nodes keep
> changing, it's necessary to decide on a specific firmware DTB which is
> decoupled from the Linux DTB (which can be loaded separately from
> U-Boot as long as the ethernet/MMC drivers are working :-).

Yes, it's annoying for ARM. Hence I believer on RISC-V the goal is to
use the firmware provided DTB for all the software on the boot chain:
OpenSBI, U-Boot, kernel. That's why U-Boot RISC-V is currently using
OF_PRIOR_STAGE.

As for the syntax of the nodes keep changing, I would say that's
inevitable because of the upstreaming process. Everything in vendor's
DT that does not get merged in Linux will remain potentially changed
by later upstreaming reviews.

>
> If U-Boot needs a specific DTB, shouldn't it be shipped in
> u-boot/arch/riscv/dts/?
>

This can be done by adding OF_SEPERATE support to RISC-V. But so far
OF_PRIOR_STAGE already works hence adding that would be of low
priority.

Regards,
Bin