[U-Boot] imx7d: CPU core issue in secure mode

Hi,

I'm trying to get an imx7d-based Colibris board running in secure mode in order to be able to use the CAAM, especially the HWRNG. However it seems like it's currently not possible to boot a mainline kernel (4.19) in secure mode with both CPU cores powered up, likely due to the missing PSCI firmware in secure mode. When booting in nonsecure mode the kernel recognizes both CPU cores while CAAM isn't working. Basically it's the same issue as discussed at

https://www.spinics.net/lists/u-boot-v2/msg33873.html

I'm using the latest mainline U-Boot (2019.07-rc4) with CONFIG_ARMV7_BOOT_SEC_DEFAULT=y. Is there anything I can do about this issue?

Thank you and best regards

Tobias