Bug#452894: Brightness is reduced when switching to a VT, using 3d games or switching resolution

["Diego Escalante Urrelo" <dieguito@gmail.com>]

On 12/3/07, Brice Goglin <Brice.Goglin@ens-lyon.org> wrote:
> Diego Escalante Urrelo wrote:
> > On 12/3/07, Brice Goglin <Brice.Goglin@ens-lyon.org> wrote:
> >
> >> That's why you need thinkpad-acpi loaded, the X driver uses the "kernel"
> >> interface.
> >>
> >>
> >
> > t-acpi *is* loaded.
>
> Ok, I am confused by all your earlier replies then. You seem to say that
> t-acpi
> being loaded does not change anything. Did you find any configuration
> (I mean "is t-acpi loaded?" + "which backlight method does xrandr report?")
> that always work or always fail?
>

Ok, let's summarise, sorry for the chaos:

1. Boot normally
2. Thinkpad acpi is loaded automagically
3. X starts via gdm
4. Brightness is reduced from 100% to 80%~70%
5. You set brightness back to top
6. You start zsnes or switch to a VT
7. Brightness goes back to 80%~70%
8. You change the backlight control via xrandr to *whatever* except kernel
9. Brightness stays at what you set

That's the flow, the output of xrandr when the problem happens is:
diego@milkyway:~$ xrandr --prop
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 1024 x 1024
VGA disconnected (normal left inverted right x axis y axis)
LVDS connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
        BACKLIGHT_CONTROL: kernel
                supported: native       legacy       combination  kernel
        BACKLIGHT: 6 (0x00000006) range:  (0,7)
   1024x768       59.3 +   85.0     75.0*    70.1     60.0
   832x624        74.6
   800x600        85.1     72.2     75.0     60.3     56.2
   640x480        85.0     72.8     75.0     59.9
   720x400        85.0
   640x400        85.1
   640x350        85.1


After setting to native:
diego@milkyway:~$ xrandr --prop
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 1024 x 1024
VGA disconnected (normal left inverted right x axis y axis)
LVDS connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
        BACKLIGHT_CONTROL: native
                supported: native       legacy       combination  kernel
        BACKLIGHT: 0 (0x00000000) range:  (0,0)
   1024x768       59.3 +   85.0     75.0*    70.1     60.0
   832x624        74.6
   800x600        85.1     72.2     75.0     60.3     56.2
   640x480        85.0     72.8     75.0     59.9
   720x400        85.0
   640x400        85.1
   640x350        85.1