Hi! > >>Triggers are not limited to periodic blinking or reporting cpu > >>activity. There is also oneshot trigger that can be used e.g. when > >>user touches the screen, as Pali mentioned. > > > >Using oneshot trigger for this would be pretty strange. > > It was only an example to mention other than periodic triggers. > You could have a trigger that just turns the LED permanently on > after user touches the screen. Well.. triggers kind of assume they control the LED. They were not prepared to deal with hardware changing the brightness behind their back. > >Notice that in > >some cases (thinkpad battery led, for example) we either have firmware > >controls the LED (but then software can't control it) or we have > >software controlling the LED (but then we don't know what firmware > >would put there). Maybe keyboard backlight can be controlled > >"simultaneously" by both software and firmware, but there are > >certainly LEDs that can't handle that, and IMO it would be nice to > >have same interface. > > > >>>Well.. actually... I think this is a little bit over complex and > >>>probably unneccessary. I'd let Hans implement whatever he thinks is > >>>easiest. > >> > >>I'd say this is the trigger approach which is a bit convoluted. > > > >In my eyes trigger approach is neccessary at least for some hardware, > >and things it pretty clear: trigger on == LED changes without > >userspace involvement. trigger off == userspace controls the LED. > > It is likely that it would break many existing users. Can you elaborate on that? I just tried with leds on thinkpad root@duo:/sys/class/leds/tpacpi::power# echo 1 > brightness root@duo:/sys/class/leds/tpacpi::power# echo 0 > brightness root@duo:/sys/class/leds/tpacpi::power# cat trigger [none] bluetooth-power kbd-scrollock kbd-numlock kbd-capslock kbd-kanalock kbd-shiftlock kbd-altgrlock kbd-ctrllock kbd-altlock kbd-shiftllock kbd-shiftrlock kbd-ctrlllock kbd-ctrlrlock AC-online BAT0-charging-or-full BAT0-charging BAT0-full BAT0-charging-blink-full-solid rfkill0 phy0rx phy0tx phy0assoc phy0radio phy0tpt mmc0 timer pattern rfkill1 hci0-power rfkill74 heartbeat root@duo:/sys/class/leds/tpacpi::power# I can control the LED from userspace, but then there's no way to put the LED back to firmware control. That's just broken. Do you have a proposal how to handle that? > >So I'd do the trigger here. It is same way we can handle LEDs on > >thinkpad. Yes, it means you won't be able to do oneshot trigger on > >backlight. I don't think that's a huge problem. > > There have been voices in this discussion claiming the opposite. :-) Well, lets ignore those voices until the voices understand the current design :-). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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