Hi Wolfram. On Tue, Mar 21, 2023 at 06:20:45PM +0100, Wolfram Sang wrote: > Hi Sascha! > > > Nice to hear from you here ;) > > Yeah, it has been only 10 years... :) > > > I have no idea how the SDRAM setup is done on the USB-A9G20. There seems > > to be SDRAM setup code for the USB-A9263, but not for the USB-A9G20. Is > > there some AT91Bootstrap required? > > Yes. There is a bootstrap required: https://github.com/linux4sam/at91bootstrap > However, an old version is needed. I am still fighting the details. > > I accidently erased it, so my journey for unbricking the device began. > at91bootstrap, openocd, barebox - they all once supported A9G20, but > nowadays all of them were broken. Well, I fixed openocd and barebox > mostly so far, the bootstrap is still the missing piece. You may be hit by the newer gcc optimize the delays in the sdram init code in at91bootstrap. This code: /* Step#4 The minimum pause of 200 us is provided to precede any single toggle */ for (i = 0; i < 1000; i++) ; Are optimized away with newer gcc's. You can find it repeated several times in the init code. I think this was the only part what broke at91bootstrap for me. It was Ahmad, IIRC, that told me about it - so not my finding. > > Super interesting about the A9263 setup code. I missed it so far. Does > that mean that barebox can replace the at91bootstrap? Yes. The patch series I pointed at generates a bare variant that I successfully used to boot my board direct from ROMBOOT. It is a direct replacement for at91bootstrap and loads barebox as the next step bootloader. I really like the way it is all integrated and how the two barebox variants are built in one go. Sam > > > Anyway, what's really missing is DT support. I scribbled a patch to get > > you started in case you are motivated. Basically it's: Compile in the > > Motivated? No way ;) Obliged? More so. But first, I want to unbrick my > device. First make it work, then make it beautiful. > > That being said, the two patches from this series are okay? I'd think > they are still needed for other legacy systems even if I convert A9G20 > to DT in some ages. > > Thanks for your help! > > Wolfram
