Re: Dell Inspiron 8100 - how to turn off LCD backlight (in console mode)?

On 11/29/2007 04:16, Torfinn Ingolfsen wrote:
I have an old laptop, Dell Inspiron 8100.
It runs FreeBSD, RELENG_6:
root@kg-i82# uname -a
FreeBSD kg-i82.kg4.no 6.3-PRERELEASE FreeBSD 6.3-PRERELEASE #2: Sat Oct 27 02:42:35 CEST 2007 root@xxxxxxxxxxxxx:/usr/obj/usr/src/sys/I81K i386

The machine has a Nvidia gfx card:
root@kg-i82# pciconf -lv | grep -B 4 VGA
acpi_video0@pci1:0:0: class=0x030000 card=0x00e61028 chip=0x011210de rev=0xb2 hdr=0x00
vendor = 'NVIDIA Corporation'
device = 'NV11 GeForce2 Go / MX Ultra'
class = display
subclass = VGA

It is used as a firewall, so it doesn't run Xorg, it only runs in console (text) mode.
I use blank_saver to turn off the screen (text), and this works. I have tested with green_saver as well, and that also works.

The problem is that the LCD backlight stays on. How do I turn it off?
Ideally, the backlight would turn off with the screensaver, and turn on when the screensaver is deactivated again.

I tried with acpi_video, which gives me this:
root@kg-i82# sysctl hw.acpi.video
hw.acpi.video.crt0.active: 0
hw.acpi.video.lcd0.active: 1

I can change hw.acpi.video.lcd0.active to 0 (zero), but the display still stays on.
It doesn't seem like the i8k have a lid switch either:
root@kg-i82# sysctl hw.acpi
hw.acpi.supported_sleep_state: S1 S3 S4 S5
hw.acpi.power_button_state: S5
hw.acpi.sleep_button_state: S1
hw.acpi.lid_switch_state: NONE
hw.acpi.standby_state: S1
hw.acpi.suspend_state: S3
hw.acpi.sleep_delay: 1
hw.acpi.s4bios: 1
hw.acpi.verbose: 0
hw.acpi.disable_on_reboot: 0
hw.acpi.handle_reboot: 0
hw.acpi.reset_video: 0
hw.acpi.cpu.cx_lowest: C1
hw.acpi.acline: 1
hw.acpi.battery.life: 91
hw.acpi.battery.time: -1
hw.acpi.battery.state: 2
hw.acpi.battery.units: 2
hw.acpi.battery.info_expire: 5
hw.acpi.thermal.min_runtime: 0
hw.acpi.thermal.polling_rate: 10
hw.acpi.thermal.user_override: 0
hw.acpi.thermal.tz0.temperature: 60.5C
hw.acpi.thermal.tz0.active: -1
hw.acpi.thermal.tz0.passive_cooling: 0
hw.acpi.thermal.tz0.thermal_flags: 0
hw.acpi.thermal.tz0._PSV: -1
hw.acpi.thermal.tz0._HOT: -1
hw.acpi.thermal.tz0._CRT: 101.0C
hw.acpi.thermal.tz0._ACx: -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
hw.acpi.video.crt0.active: 0
hw.acpi.video.lcd0.active: 1

There isn't an acpi_dell or acpi_i8k module, at least I haven't found one.
I have searched quite a bit on Google, but haven't found anything helpful.

Any hints on how to get the backlight to turn off and on again (synced to the console screensaver)?

IMHO, either of the acpi, apm or sc driver should have taken care of backlight control and, or display power management. The manpage for apm(4) clears this doubt:

BUGS
WARNING! Many, if not most, of the implementations of APM-bios in
laptops today are buggy. You may be putting your LCD-display and
batteries at a risk by using this interface. (The reason this is
not a problem for MS-Windows is that they use the real-mode
interface.) If you see any weird behavior from your system with
this code in use, unplug the power and batteries ASAP, if not
immediately, and disable this code.

We are very interested in getting this code working, so please send
your observations of any anomalous behavior to us.

When apm is active, calling the BIOS setup routine by using
hot-keys, may cause serious trouble when resuming the system. BIOS
setup programs should be called during bootstrap, or from DOS.

Some APM implementations cannot handle events such as pushing the
power button or closing the cover. On such implementations, the
system must be suspended only by using apm(8) or zzz(8).

Disk spin-down, LCD backlight control, and power on demand have not
been supported on the current version.

FreeBSD 7.0 November 1, 1994 FreeBSD 7.0

FYI, though the above looks like a page from FreeBSD 7.0, but I currently am running FreeBSD 8.0-CURRENT on my DELL Inspiron 4150/1.8GHz/256MB/40GB machine.

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