Hello Eugen, Am Mon, Oct 21, 2024 at 10:17:54AM +0300 schrieb Eugen Hristev: > Hello, > > On 10/21/24 09:03, Alexander Dahl wrote: > > Hello Benedikt, > > > > Am Fri, Oct 18, 2024 at 04:19:08PM +0200 schrieb Benedikt Spranger: > > > On Fri, 18 Oct 2024 15:11:20 +0200 > > > Alexander Dahl <a...@thorsis.com> wrote: > > > > > > Hello Alexander, > > > > > > > Am Fri, Oct 18, 2024 at 10:30:00AM +0200 schrieb Benedikt Spranger: > > > > > OK, you might say the nand_atmel NAND driver is obsolete, but it > > > > > was the only solution to get booting from NAND running. The new DM > > > > > based NAND driver refused to do anything usefull, so I dropped it > > > > > after spending a couple of days debugging it: > > > > > > > > Strange. I have at least three different boards with SAMA5D27 > > > > successfully booting from NAND flash with the new DM based driver > > > > (unfortunately none of them upstreamed, which also won't change in the > > > > foreseeable future, sorry). > > > OK. > > > > Do you use at91bootstrap as 2nd level bootloader like me or something > > > > else? > > > I use the U-Boot SPL. There is no UBI support in at91boostrap. There > > > were some attemps, but... > > > No interest at the at91bootstrap side. > > It's not about interest. There are two main reasons: > First, all open source UBI stacks are GPL. At91bootstrap is not GPL and it > cannot take GPL restricted code (being MIT ). > Second, all UBI stacks are huge in terms of code and memory. At91bootstrap > is a second stage that should fit in 16k , 32k or 64k depending on the > platform. So far this restriction could not be met by any UBI > implementation. > ... and yes, doing a custom in-house small UBI implementation would be > challenging, and costly.
I suspected technical reasons, but nice to know it's also licensing. (Side note: To increase robustness we considered storing bootloaders (and maybe U-Boot env) in SPI-NOR flash with longer data retention, and use UBI on raw NAND for everything else.) > > > > > Yeah, been there. Wanted at91bootstrap to boot from SPI-NOR which is > > _not_ Quad-SPI, and the feature request was closed with "if you wanna > > do it by yourself, ask our support for help". :-/ > > iirc at91bootstrap can boot from raw spi-nor (yes, not UBI) Speaking of at91bootstrap 3.x and later: It can, but only if you use the QSPI port, it does not work with flexcom for example. See https://github.com/linux4sam/at91bootstrap/issues/181 for reference. > > > > > > For me it was basically getting the dts for U-Boot correct, but > > > > I got that running with all U-Boot releases since 2023.04 up to > > > > 2024.10. Could you share some more detail? > > > I face all the trouble in SPL. And since the SPL is the essential part > > > here (UBI support) I gave up at one point. I simply couldn't any > > > usefull read data from the NAND flash, but all 0. > > > > You can not store bootstrap or SPL in UBI, it must sit in first sector > > of raw NAND, I suppose that's how you load SPL? Did you try > > reading/writing raw NAND from there? I'm not familiar with SPL, does > > it consider dts? I could share my dts parts if that helps you. > > SPL should use dts. However on at91 platforms, SPL is dangerously close to > the SRAM limit where it should fit, and it has been challenging in the last > years to either make it fit or remove it. > > > > > (What I do here: SoC loads at91bootstrap from raw NAND at offset 0, > > at91bootstrap loads U-Boot from raw NAND at some offset like 0x20000, > > U-Boot (proper) loads everything else from UBI.) > > Either way, it is interesting to see that the U-boot proper NAND dm driver > does not work without at91bootstrap. > There may be NAND quirks in at91bootstrap board init that may influence this > (pins resets, timing delays, etc). Think this is a misunderstanding here. I have this combination running, and from the discussions on NAND issues on at91 on this list I think at least two developers at Microchip, too. From my understanding U-Boot proper completely (re)initializes everything required to get NAND to work. I can not speak about U-Boot SPL though, never tried that. > You can test NAND driver by booting at91bootstrap and Uboot from another > medium, like sd-card. In this way, at91bootstrap will not touch NAND device, > and you have a clean U-boot booted. Lets hear what Benedikt has tried. ;-) Greets Alex
