[TF-A] suspend to ram on rk3399 theobroma puma

Hi all!

We are developing a product around the rk3399 Theobroma Q7 module. For power savings, we need S3 sleep (suspend-to-ram).

As far as I know, the heart of this is in ATF code. We have linux kernel 5.4, which starts the process nicely, drives down all the other cores and finally calls for the psci suspend. We have wakeup on irq, and it sure wakes up, but does a reset from the very beginning. So no context saving resume.

I have tried the newest on the ATF git, with a newish mainline uboot. I suppose the role of uboot is not that important here.

What should I look at to find the problem? Has someone got the Q7 module done S3 ok?

Finally, how do I get some debug uart output from ATF code?

Thanks for any hints!

Mika Penttilä