Re: [PATCH v2 4/5] ARM: Add basic support for Airoha EN7523 SoC

Hi Arnd,

On Tue, 7 Sept 2021 at 20:52, Arnd Bergmann [off-list ref] wrote:

quoted

Off-topic but related:  Another MediaTek spin off, SigmaStar, seems to
have done exactly the same thing. Cortex A53 chip running as a 32bit
system to avoid having to fix their software. I'm interested to see if
this makes it into arm or arm64. :)

Maybe it's best to just add them to both at the same time? The boot
loader situation might take a bit to work out, but in theory this should
be fixable.

I wonder how fixable it would be..

I haven't gotten a board with the chip in question (SSD268G) yet but
from looking at some firmware binaries I can see that even u-boot is a
6 year old 32bit version.
As far as I can tell there's no PSCI, ATF etc that I think would be
expected for an arm64 machine.
I think the broken memory controller is still there so somehow I'd
need to get the heavy barrier to work in arm64. I haven't yet worked
out if that's even possible.
I think they are advertising that it supports up to 2GB of DDR. So
it's a hobbled 64bit capable system with highmem.

Putting most of the DT bits under arm64 even though it's so broken
it'll only ever boot a 32bit kernel makes sense to me.
Better than having lots of arm64 typical stuff like a newer GIC in a
file under arm and confusing everyone that comes across it.

Cheers,

Daniel