Double brightness events

Joonas Saarinen jza at saunalahti.fi
Tue Nov 25 08:10:53 UTC 2014


Hi Jackson and others,

I have seen many variations of this bug being posted in Launchpad, 
regarding different laptops.

But here's one quite coherent one:
https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/527157

Some other occurrances of the same problem:
https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/802276
https://bugs.launchpad.net/gnome-power/+bug/839281
https://bugs.launchpad.net/ubuntu/+source/fglrx-installer/+bug/839788
https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/1000270

Then there is an AskUbuntu thread which lists the typical workarounds:
http://askubuntu.com/questions/173921/why-does-my-thinkpad-brightness-control-skip-steps/178003

Best regards,
Joonas Saarinen

On 2014-11-24 23:56, Jackson Doak wrote:
> Has a launchpad bug been created for this?
>
> On Thursday, November 13, 2014, Joonas Saarinen <jza at saunalahti.fi
> <mailto:jza at saunalahti.fi>> wrote:
>
>     Hi,
>
>     For years, Ubuntu has had this bug where a lot of laptops react to
>     brightness adjustment in steps of 2 (or even 3). I believe this is
>     not by design (correct me if wrong).
>
>     It seems that the brightness keypress is handled in multiple places.
>     Possibly the OS does the adjustment, but does not consume the event
>     and then BIOS does another adjustment.
>
>     Some machines can be fixed with this trick:
>     # echo N > /sys/module/video/parameters/__brightness_switch_enabled
>
>     Are there plans to fix this bug? It's quite obvious one and
>     immediately strikes you when you install and start using Ubuntu on a
>     laptop.
>
>     Some affected laptops: Dell E4300, Asus F200CA, HP 6910p, Fujitsu
>     E751...
>
>     Joonas Saarinen
>
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