Comment # 29 on bug 1212877 from Stefan Wahren

At first I think we should clarify some wordings. Suspend to RAM is currently
not support for all Raspberry Pi products and it's very unlikely it will ever
be [1].

But suspend to idle is "easier" to achieve and i'm active working on this since
July 2024 [2]. Since the Raspberry Pi got more and more complex with every
generation, I decided to start with the old Rpi 1. Currently there are two
drivers (vc4 & dwc2), which doesn't have full suspend to idle support in
current Mainline. Unfortunately the interest for this feature doesn't have high
priority and most of my questions doesn't get a feedback. So it's mostly trial
& error and I don't know how far the suspend to idle will ever be supported.

My current working branch is here [3]. Every Rpi until the 3rd generation
should work. And the latest patches should allow experimental CM4 testing. So
test feedback is welcome.

[1] - https://github.com/raspberrypi/linux/issues/1281
[2] - https://github.com/lategoodbye/rpi-zero/issues/9
[3] - https://github.com/lategoodbye/linux-dev/commits/v6.13-pm/