On 11/25/2016 09:40 PM, Pavel Machek wrote: > 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? There might exist users that adjust LED brightness while having active trigger. The best example is default-on trigger - it sets brightness only on init, but remains active all the time. Whereas this could be fixed, there is another case: think of changing blinking brightness - it would be impossible. > 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? Isn't it under firmware control all the time? > >>> 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 :-). Sheer user is not interested in design, but in usability. -- Best regards, Jacek Anaszewski ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ ibm-acpi-devel mailing list ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/ibm-acpi-devel
