Is wake-up pin used by any driver?


Using device tree customization, I’ve successfully disabled SODIMM45 for wake-up in order to use it as a GPIO (actually removed the whole gpio-keys node), since we won’t be using any wake-up signal whatsoever. However I’m a bit concerned that this is kind of a delicate pin and maybe some driver(s) are actually using and using it as GPIO could lead to unexpected behaviors since “it doesn’t expect to be removed” or “it needs a wake-up input”. I know what is important is the wake-up signal itself and that gets disabled by disabling the pin function, but better safe than sorry…

Is there any documentation (without to having to look at the whole kernel documentation) of a pin dependency which could lead to unexpected behaviors? In this specific case, should I avoid using SODIMM45 for GPIO?


With the advent of device tree all such dependencies should be part of the device tree (e.g. a GPIO/pinctrl node would be linked to a device driver, if that device driver needs to make use of it). So searching through the device trees should be sufficient. In this case, neither the GPIO (“gpio1 9”) nor the pin (“pinctrl_gpiokeys”) is used anywhere else, and the whole gpio-keys/power node is also not referenced from other drivers. It is safe to use SO-DIMM 45 as a regular GPIO after removing the wake-up GPIO key node.