How to change DRAM size in Yocto U-Boot for iMX6

[acompagni]

Hello Everyone,
I have a board based on imx6ullevk, with 256MB of DDR instead of the original 512MB.

I have created my custom layer and custom machine in Yocto environment but I'm having issues trying to change the DRAM size.

I have modified the memory define "PHYS_DRAM_SIZE" but I can't make the change effective once I've compiled my SD card image.

Is there a guide I can follow that shows exactly what to do to customize the u-boot parameters?

Thank you

Andrea

[gusarambula]

Hello  Andrea Compagni,

The closest thing to a guide on the documentation would be the i.MX BSP Porting Guide which is part of the BSP Releases documentation.

You would need to change the DCD table for the i.MX initialization, which depends on the timing and characteristics of the new RAM rather than just the size. You can see more details on this on the section “Changing the DCD table for i.MX DDR initialization”.

You would also need to edit the device tree with the new size information. In your case it could be that even tough you are changing the source code for uboot it is being overridden by the configuration data from the bootloader recipe. I would recommend extracting the toolchain and compiling the bootloader independently to test it. Once it’s working correctly you could then create a patch and append it to the Yocto bootloader recipe.

I hope this helps!

Regards,