Subject: Re: HEADS UP: ACPI-CA 20050408 imported to -current
To: None <>
From: Takayoshi Kochi <>
List: current-users
Date: 05/10/2005 11:39:05
Hi Dan,

From: Daniel Carosone <>
Subject: Re: HEADS UP: ACPI-CA 20050408 imported to -current
Date: Mon, 9 May 2005 09:36:33 +1000

> I have an oddity. I'm not certain that it's due to this change, but it
> started at just about the right time.
> My laptop screen has suddenly developed the habit of powering off the
> backlight.  Not the actual LCD, since I can (just) make out the image,
> but the light only.  Nothing I do, directly, will make it come back on.
> However, as i just discovered, if the X server sets DPMS off (after
> the 10 mins or whatever timeout, or via a manual 'xset dpms force
> off'), and I then hit a key, the backlight comes on again.

Hmm, the current NetBSD ACPI doesn't do any power-saving stuff
proactively, so it shouldn't do backlight on/off, maybe
magical SMM (x86 System-management mode) related.

Do you have any idea what is triggering the backlight off
(some idle time or low battery state etc.)?

> I can't spot any pattern as to when it decides to do it.  It will stay
> on fine for hours, and then suddenly get into a state where it will go
> off seconda after coming on again.
> Dell Latitude C600, BIOS A.22, ACPI dumps available on request.

Could you send the raw dump (not disassembled) privately?
(Though I'm not confident at all I can find anything useful in
ACPI tables...)

Takayoshi Kochi