ppd is changing main battery charger_type

While debugging why during boot the 5V boost output of a micro-usb port on a x86 tablet was getting turned off I learned that ppd is writing to /sys/class/power_supply/bq24190-charger/charge_type during boot. This causes the bq24190_charger driver to switch from OTG 5V boost mode back to charging mode, removing the power from any attached USB peripherals.

I guess that the intention of the src/ppd-action-trickle-charge.c code is to put any attached peripherals which are charging from the laptop in to trickle-charge mode. But in this case it is actually changing the setting on a scope=="System" power_supply class device which seems undesirable.

Also it might be a good idea at least at daemon-startup to check if the mode already is what it should be and to not write to sysfs in that case to avoid any side-effects like this.

Note I'm preparing a kernel fix for this as well, since the bq24190_charger driver really should just remember the requested charge mode in this case and only apply it when switching back from OTG 5V boost mode to charging mode.