[PATCH 1/3] treewide: Remove OF_PRIOR_STAGE from RISC-V boards

[Ilias Apalodimas]

Hi Mark, 

On Wed, Sep 29, 2021 at 02:59:10PM +0200, Mark Kettenis wrote:
> > > > > >

[...]

> > > > > > I was wondering if we need to check CONFIG_OF_BOARD here? I'm not sure
> > > > > > whether we should distinguish the value of a1 register which is
> > > 
> > > Yes, it seems to me that we could use a config to separate the case
> > > between the prior stage and the _end. 
> > 
> > Untangling OF_SEPARATE and OF_BOARD is part of a bigger revamp I wanted to 
> > do on the handover of a device tree from previous bootloaders,  since we do 
> > have similar 'problems' in Arm and TF-A.  But in principle OF_SEPARATE
> > shouldn't have per board code to overwrite it.  OF_BOARD should be used for
> > that.  OF_SEPARATE should merely mean "The dtb is concatenated to my U-Boot
> > binary.
> > 
> > Right now RISC-V uses OF_SEPARATE reads the DTB on SPL and then goes back
> > to using the a1 register for U-Boot proper.  We could instead read the 
> > U-Boot concatenated DTB always in that case.  OF_BOARD would then be used in
> > case OpenSBI is compiled with a *different* DTB and you'd want to use that.
> > Any idea if OpenSBI performs fixups before handing over the dtb in a1?
> 
> It does.  One of the things it does is add a reserved memory entry for
> itself.
> 

Ah lovely :(, then untangling that is not an option atm :(.  We still have
to keep board_fdt_blob_setup() a __weak symbol for those boards, even if
OF_SEPARATE is selected.

> > Unfortunately I don't have a board to test apart from QEMU.  Let me respin
> > this, with a potential fix I have in mind and we can discuss further.
> > 
> > > Just note that, there is a patch
> > > on the fly, it modifies the same snippet of code, you might need to
> > > update your code based on top of it.
> > > https://lists.denx.de/pipermail/u-boot/2021-September/460378.html
> > 
> > I'll reply to that and see if the _end is indeed a problem.
> > 
> > Thanks
> > /Ilias
> > 
Thanks
/Ilias