Problem with Dell laptop's backlight on resume

Problem with Dell laptop's backlight on resume

[Alan Stern]

With 2.6.14-rc4, when I suspend and resume my Dell Inspiron 4000 laptop
the backlight doesn't act as it should.  (BTW this behavior has been 
unchanged for many kernel releases.)

When I go to standby, the backlight remains on.

When I suspend to memory, the backlight remains on and the screen goes 
blank -- a rather disconcerting fully-white screen.  Then when I resume 
the backlight turns off, making the text-mode console invisible.  
Fortunately switching to-and-from an XFree86 screen gets the light back 
on.

Is there any way to figure out what's wrong and fix it?

Alan Stern



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Re: Problem with Dell laptop's backlight on resume

[Erik Slagter]

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On Sun, 2005-10-16 at 13:57 -0400, Alan Stern wrote:
> With 2.6.14-rc4, when I suspend and resume my Dell Inspiron 4000 laptop
> the backlight doesn't act as it should.  (BTW this behavior has been 
> unchanged for many kernel releases.)
> 
> When I go to standby, the backlight remains on.
> 
> When I suspend to memory, the backlight remains on and the screen goes 
> blank -- a rather disconcerting fully-white screen.  Then when I resume 
> the backlight turns off, making the text-mode console invisible.  
> Fortunately switching to-and-from an XFree86 screen gets the light back 
> on.

This is a known problem with the 4000's. I don't think it will ever work
right. Better focus on software suspend (aka suspend to disk).

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