I got one step closer to finding out how low modes are supposed to work. When I boot the TPT10 in rescue mode or some other single user mode with just framebuffer console enabled, the device will indeed go into a low power mode when the „freeze“ state is activated! And it wakes up by pressing the power button!

But after resume / wakeup I get a kernel error about an interrupt that was enable but no driver took it up – it is IRQ9 which in my case is the ACPI interrupt. Makes somewhat sense that it fires but why does the ACPI driver not take care of it? Even worse, why was it left enabled when going to sleep? Strange. The result is that the kernel disables the interrupt and thus s second freeze will not be able to wakeup again. But this should be fixable…

The rally bad issue is, what causes the freeze to fail when not in single user mode? A driver? X? This will be nasty to pinpoint and debug… And my final concern is the battery gauge. I still did not find any driver or setting to get a battery reading. The ACPI DSDT contains a lot of info about the battery but I still have no real idea what to make from this.