Arch Linux

Rad3k

Member

From: Poland

Registered: 2009-05-09

Posts: 36

[SOLVED] MSI Wind U100 - display blanking not working with Intel KMS

Hi there,
recently I've installed Arch on MSI Wind U100 netbook, and I'm having an issue with display blanking.

Hardware: (lspci)

00:00.0 Host bridge: Intel Corporation Mobile 945GME Express Memory Controller Hub (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GME Express Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)

The Problem:
After some time of inactivity the display turns off (as it should), but then, almost immediately turns on again. It happens in both X and text VTs.

My Findings:
I've spent some time investigating, and here's what I 've found out:
The display correctly turns off if treated with "setterm -blank force" from console or "vbetool dpms off" (dpms standby or suspend also works).
In X, with xfce4-power-manager running, when display tries to blank, the brightness control popup appears, but the brightness level doesn't actually change.
In console, "setterm -blank 1; sleep 55; showkey" shows that when display is blanking, the keycode 224 press and release is being generated (twice). This is the keycode of "reduce brightness" Fn key. This keypress is also generated when turning display off with "setterm -blank force", but not when using "vbetool dpms [off|standby|suspend]".
I didn't find anything relevant in dmesg output, and failed blanks don't produce kernel messages.

It seems that whenever the display tries to go to sleep, the "reduce brightness" keypress is being generated, which in turn wakes is up again. Only when a blank is forced it remains off because then it doesn't wake on keypresses.

I tried with KMS off, appending "i915.modeset=0" to kernel at boot, and then the issue was gone - there was no keypress generation during console blanking and it worked. But as I need KMS to start X, this is not an acceplable workaround.
I also tried appending "acpi_backlight=vendor" to kernel, which also kind of "solved" the problem, but it disabled the brightness control altogether, so again, this is not what I wanted.

I've also noticed, that the brightness control popup from xfce4-power-manager is greatly lagging behind the brightness changes (Fn keys), sometimes even to the point of not showing up at all. I don't know whether it's related, but on the other laptop I've tested it (where I have no problem with display blanking), the brightness control popup follows keypresses almost immediately.

I don't know what's the source of these weird keypresses - is this a bug in the driver, or something else?
Do you have any suggestions?

Last edited by Rad3k (2010-04-18 01:59:24)

lagagnon

Member

From: an Island in the Pacific...

Registered: 2009-12-10

Posts: 1,087

Website

Re: [SOLVED] MSI Wind U100 - display blanking not working with Intel KMS

I had a similar sort of problem and used the following:

sleep 1 && xset dpms force off

That may or may not work for you...

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Philosophy is looking for a black cat in a dark room. Metaphysics is looking for a black cat in a dark room that isn't there. Religion is looking for a black cat in a dark room that isn't there and shouting "I found it!". Science is looking for a black cat in a dark room with a flashlight.

Rad3k

Member

From: Poland

Registered: 2009-05-09

Posts: 36

Re: [SOLVED] MSI Wind U100 - display blanking not working with Intel KMS

I had a similar sort of problem and used the following:

sleep 1 && xset dpms force off

That may or may not work for you...

It doesn't work for me - it immediately turns on again.
But the problem is not that I can't force the display to turn off, but that it will *never* turn off automatically to save power when not used.

lagagnon

Member

From: an Island in the Pacific...

Registered: 2009-12-10

Posts: 1,087

Website

Re: [SOLVED] MSI Wind U100 - display blanking not working with Intel KMS

Do you have "xscreensaver" installed -that should do it for you...

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Philosophy is looking for a black cat in a dark room. Metaphysics is looking for a black cat in a dark room that isn't there. Religion is looking for a black cat in a dark room that isn't there and shouting "I found it!". Science is looking for a black cat in a dark room with a flashlight.

lucke

Member

From: Poland

Registered: 2004-11-30

Posts: 4,018

Re: [SOLVED] MSI Wind U100 - display blanking not working with Intel KMS

Update the BIOS.

Rad3k

Member

From: Poland

Registered: 2009-05-09

Posts: 36

Re: [SOLVED] MSI Wind U100 - display blanking not working with Intel KMS

Update the BIOS.

It helped
Thanks!