Re: 2.6.21-rc1 dims my LCD

[Henrique de Moraes Holschuh <hmh@hmh.eng.br>]

On Mon, 26 Feb 2007, Jiri Kosina wrote:
> On Mon, 26 Feb 2007, Richard Purdie wrote:
> > > When I hit the keyboard, the brightness stays low (it's 50% of light 
> > > or so, so I could read what's on the screen, but it's uncomfortably 
> > > dim), and I have to manually raise the brightness on the LCD. Quite 
> > > annoying :) I have bisected this to your commit 
> > > 994efacdf9a087b52f71e620b58dfa526b0cf928
> > Which framebuffer driver and backlight driver are you using?
> > ("ls /sys/class/backlight/" will show which backlight it is)
> 
> It's IBM:

Please add me to the CC, then.  I noticed this thread by accident.

> $ ll /sys/class/backlight/
> drwxr-xr-x 2 root root 0 Feb 26 13:28 ibm
> 
> At the time the brightness goes low, there is '0' in 
> /sys/class/backlight/ibm/actual_brightness and 
> /sys/class/backlight/ibm/brightness

ibm-acpi does not implement display poweroff, so if a screen-saving function
on the kernel is trying to use it to shut the display off, it will either
fail to do anything, or if it ALSO sets brightness to zero, it will just dim
the display.

Richard, would you like a patch to -ENOSYS if a display power management
event reaches ibm-acpi?

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh