GNOME Bugzilla – Bug 728971
Backlight levels differ going from top-to-bottom vs bottom-to-top
Last modified: 2019-02-01 14:15:36 UTC
The backlight levels from top-to-bottom proceed as follows: 100,86,72,57,43,29,15,0. [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (86,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (72,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (57,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (43,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (29,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (15,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown (0,) From bottom-to-top they are different: 0,14,28,43,57,71,85,100 [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (14,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (28,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (43,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (57,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (71,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (85,) [conley@styrka ~]$ gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp (100,) This has to do with the rounding apparently, though I haven't found the error yet. This would be a good Gnome Love/Papercuts bug.
How is this actually a problem? A 1% difference in backlight is hardly visible.
It's simply a matter of polish; it would be a good candidate for a papercuts or gnome-love bug. It would be nice to have consistent behavior going both ways. It seems obvious to point out that reversible behavior *should* behave in a consistent way. You can close the bug if you would like, though.
Probably something odd happening with the rounding. The code has changed considerably, but I suspect that this may still happen. Anyway, I don't feel like this is problematic enough to take action. If anyone wants to work on ensuring we round/step consistently, then feel free to submit a patch. Please note, that I believe it will be a lot less relevant on modern machines as we have a lot of brightness steps there.