Subject: Re: [wscons] Switching off backlight of LCD ?
To: Heiko W.Rupp <>
From: Matthias Drochner <>
List: current-users
Date: 09/04/1999 14:54:18
[screen powersafe in wscons] said:
> Hm. I gues this would be the best place though. 

OK, I'll add an ioctl to the vga driver.

> From looking at the rev 1.2 bios interface
> spec, it looks like the Set Power State command (0x07) with device id
> 0x01xx and Power state 0x03 could do the trick.

I've read this -- the question is "what is the xx in 0x01xx".
How do I know which devices are supported at all and how they
map to NetBSD devices? Try and error?

There is a PnP BIOS call which could help here:
"Get APM ID Table", which returns a table of
PnP IDs (== EISA identifier) and APM device ids.
But PnP deals only with onboard devices, and doesn't
handle PCI devices on most boards as far as I've tried.

So I think the graphics driver has to handle this.
(Dunno what ACPI provides.)

> when wscons
> just had two hooks, that call a external tool after some time without
> activity (blank screen) and to redisplay

This would a good way to get a screen saver without much
kernel bloat. The interface needs some thoughts...

best regards