[PATCH 0/3] mtd: nand: atmel: legacy: fix boot on USB-A9G20

[Sascha Hauer]

On Tue, Mar 21, 2023 at 10:42:21PM +0100, Wolfram Sang wrote:
> Hi,
> 
> > > It is a direct replacement for at91bootstrap and loads barebox as the
> > > next step bootloader.
> > The above is entirely correct - as the barebox variant supports booting from
> > SD card only, where at91bootstrap support additional boot sources.
> 
> So, I quickly built the bootstrap for A9263 and it was ~71KB in size.
> This is OK for the A9263 with 96KB of SRAM, but the A9G20 only has
> 2x16KB. So, I think I'll need to update at91bootstrap to unbrick my
> device. at91bootstrap is ~4-5KB from what I observed. But thanks for the
> inspirtation!

The barebox way to do that is to put an SD card driver (or whatever your
bootsource is) into the PBL, then let the boot ROM just load the PBL
part of the image. In the PBL configure SDRAM, use the SD card driver to
load the rest of the image (or the full image again) into SDRAM and jump
to it.

That might be out of scope for you right now as it requires some more
work.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |