Hello, now in linus tree appeared new support for brightness_hw_changed sysfs attribute which provides poll() for reporting brightness changes from hardware itself. But this support is useful just for one single central userspace application which will control all leds in system other application which will change state by /sys/class/leds/ will de-synchronize that one central application. On linux system it is normal that more userspace application could change brightness level and to make them happy and synchronized with kernel state all those application should know that there was change (by other application) of brightness level. Currently they will know only about change done by hardware itself. So I think new ABI is not sufficient and I would propose to add poll() support also for changes done by userspace, write() to attribute /sys/class/leds/.../brightness. -- Pali Rohár pali.rohar@xxxxxxxxx
