Re: 2.6.21-rc1 dims my LCD

[Jiri Kosina <jikos@jikos.cz>]

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:

$ 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

Echoing '7' into /sys/class/backlight/ibm/brightness gets the brightness 
back again to normal.

> Is the machine in active use when it dims or at idle and does the screen 
> blank at the same time it dims? If so, does the keypress unblank the 
> screen (but not change the brightness)?

It doesn't blank at the time it dims - it just decreases brightness. I 
will do some more tests, but it seemed on a first sight that it happens 
only when the machine is idle.

> Also, is this on a console or under something like X? 

I observed it only on console, but didn't experiment with it too much yet.

-- 
Jiri Kosina