# Re: \[Bugme-new\] \[Bug 40492\] New: FB\_BACKLIGHT should be set by

- From: Michel Dänzer \<hidden\>
- Date: 2011-08-04 05:55:16 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2011/08/13461834
- Thread: https://ratatoskr.run/linux-fbdev/2011/08/13461833/t.md

```text
On Mit, 2011-08-03 at 17:55 -0700, Randy Dunlap wrote: 
> On Wed, 3 Aug 2011 18:55:41 GMT bugzilla-daemon@bugzilla.kernel.org wrote:
> 
> > https://bugzilla.kernel.org/show_bug.cgi?id@492
> > 
> >            Summary: FB_BACKLIGHT should be set by BACKLIGHT_CLASS_DEVICE
> >            Product: Other
> >            Version: 2.5
> >     Kernel Version: 3.0.0
> >           Platform: All
> >         OS/Version: Linux
> >               Tree: Mainline
> >             Status: NEW
> >           Severity: normal
> >           Priority: P1
> >          Component: Configuration
> >         AssignedTo: other_configuration@kernel-bugs.osdl.org
> >         ReportedBy: StormByte@gmail.com
> >         Regression: No
> > 
> > 
> > Created an attachment (idg432)
> >  --> (https://bugzilla.kernel.org/attachment.cgi?idg432)
> > Kernel's config
> > 
> > I discovered a scenario in which menuconfig fails to set FB_BACKLIGHT symbol
> > when needed.
> > 
> > In my case, I have propietary nvidia drivers once loaded Xorg, but in the
> > meanwhile, I have configured an uvesafb framebuffer (thus, no other framebuffer
> > active nor compiled).
> > 
> > System works ok, but when trying to install nvidiabl[1] (to control nvidia's
> > backlight) I find that FB_BACKLIGHT is not set where it should be because I
> > have BACKLIGHT_CLASS_DEVICE set.
> > 
> > The result is that nvidiabl does not compile.

Sounds like an nvidiabl bug. I'm successfully using backlight control
with radeon KMS with

# CONFIG_FB_BACKLIGHT is not set
CONFIG_BACKLIGHT_CLASS_DEVICE=m


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer
```