My understanding is the same. I assume the modem chip keeps powered on and can activate an IRQ line to wake up the SOC.As per my understanding in suspend mode running state of system is saved in RAM, and power supply to all other parts excluding RAM is cut off. So how did pinephone is able to detect incoming call in suspend mode, and what triggers it to come out of suspend mode ?
The SOC has that IRQ line configured as a wakeup source. (and the touchscreen, keyboard, etc. too, maybe also a timer).
In the Pyra schematics I see a MODEM-WAKEUP 11.3B line that goes to pin 41 of the Board to-board connector. It seems to be connected to GPIO1_WK15/28.1A on the CPU board and go to U2201GPIO1_WK1 on the OMAP5432 CPU.
Before one can use that the kernel must be able to suspend (or hibernate) and resume correctly, of course.
But maybe it would be worth investigating the PinePhone software closer, if someone plans to use the Pyra as a phone.
Not sure it does? Just tested mine, and it doesn't wake up for a call.
Correction - my PinePhone did apparently try to wake up. It just crashed in the process.
Maybe you can update your software somehow with the changes Lukasz Erecinski attributed to Ondrej (Megi) Jirman ?
Or just wait till some update to the software you are using picks them up ?
I have no idea, just lurking in other people's forums.