DDR Calibration on Non-SPL u-boot

We’re facing temperature related DDR stability issues that have been fixed by Toradex in BSP 2.8b4: Toradex System/Computer on Modules - Linux BSP Release .

Using BSP V2.6 for various reasons, we’re still stuck with non-SPL u-boot configuration and therefore cannot directly backport the DDR initialization and calibration from the newer BSP. We already tried to backport from u-boot-toradex 2016.11. The calibration was inserted in the boards dram_init()-function (see here) but the calibration is stuck at step #4 & 5. of the mmdc_do_write_level_calibration() routine (see here).

Has anyone successfully implemented DDR write level calibration and dqs calibration in a non-SPL u-boot?
Is it even possible?

Any help is very appreciated.


Easiest would be to just update to at least a later U-Boot version which should still be able to boot a former Linux kernel. Maybe slight adjustments (e.g. uImage vs. zImage) need to be done…

Thanks for the reply.
What does that exactly mean (which versions would you suggest) and how to do it?
We tried both adapting the source code from 2016.11 to 2015.04 and using the whole u-boot-toradex recipe from BSP 2.8.7 (which I had to give up because it’s too difficult for me).

HI @gal-swt

You are welcome.

We already tried to backport from u-boot-toradex 2016.11

So either you can just use Bsp 2.8b7 out of box, which is our LTS release or you would need to adjust U-Boot from Bsp 2.8b7 to make boot your specific kernel.

By the way, why do you need to use Bsp 2.6? This is a very old kernel and not supported any more by Toradex.

Best regards,

Hi Jaski,
thank you for the response!
Meanwhile I had a converstation with the authors of the calibration. Now the issue is more clear to me: U-Boot cannot run the dynamic calibration because it is running from RAM whereas SPL runs from the OCRAM. This was not clear to me beforehand…
We will evaluate if static DDR calibration for the Colibri Module will solve the problem as well.

Best regards,

Hi Lukas
You are welcome.

Let us know if your issue was solved.

Best regards,