Bug 451180 - No display backlight when resuming eeepc from sleep
No display backlight when resuming eeepc from sleep
Product: Fedora
Classification: Fedora
Component: pm-utils (Show other bugs)
All Linux
low Severity medium
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Assigned To: Phil Knirsch
Fedora Extras Quality Assurance
Depends On:
Blocks: FedoraMini/Mobility
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Reported: 2008-06-13 04:39 EDT by Carlo Raudino
Modified: 2015-03-04 20:19 EST (History)
5 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2008-06-14 06:49:23 EDT
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Description Carlo Raudino 2008-06-13 04:39:15 EDT
Description of problem: Resuming eeePC 701 from sleep, results in no
backlight... for getting light back, you need to press FN+F4 (backlight
controls) and brightness come back

Version-Release number of selected component (if applicable):
fedora 9 full updated

Actual results:
We got it working, with this workaround:

This works for the eeepc701. But doesn't work in eeepc901. In this last one, the
user must HARD RESET.... no way to resume backlight.

Expected results:
Display brightness resuming, without tweaks
Comment 1 Richard Hughes 2008-06-13 06:01:34 EDT
Have you tried "pm-suspend --quirk-reset-brightness" ?
Comment 2 Carlo Raudino 2008-06-13 06:15:34 EDT
Tried now in my eeepc 701:

using pm-suspend --quirk-reset-brightness

at resume I have brightness at 125 % (it's brighter than usual maximum) , and I
can't change the brightness using Fn keys (they usually work directly, also
while loading OS)

cat /sys/devices/platform/eeepc/brn

(wrong value...)

It would be nice to test this command in eeepc 900/901, that can't resume with
the lamer workaround (reading value and setting it)

Any idea?
Comment 3 Richard Hughes 2008-06-13 07:19:14 EDT
>cat /sys/devices/platform/eeepc/brn

Why isn't the kernel using a standard brightness class?

Does xbacklight also change the brightness on this PC?
Comment 4 Carlo Raudino 2008-06-13 08:00:06 EDT
how to try it? can you tell what to do, to test it out?

ps gnome-power-management seems to not see the "brightness"..... I remember with
other distributions, it was able to change brightness...for example, with pc
Comment 5 Bastien Nocera 2008-06-13 14:30:09 EDT
xbacklight isn't shipped by default, it's available here:

This uses the X.org driver to set the brightness, and not any kernel bits. Try
it out in X, and see if it allows the brightness to change again after a resume.
Comment 6 Carlo Raudino 2008-06-13 15:00:23 EDT
I disabled my workaround (so, stock 99video)

suspended using: pm-suspend --quirk-reset-brightness

Resumed (brightness 125 %....)

xbacklight, gives me  "100%" value

I setted with xbacklight, 50 %..... no change.... but xbacklight reports 50 %..

strange... it's like a "broken" link between hardware and software....
Comment 7 Carlo Raudino 2008-06-13 15:07:45 EDT
Now (rebooted) I tried:

stock 99video script
NORMAL SUSPEND (without --quirk-reset-brightness)

after resume (black screen....resumed pressinf Fn+F4)

xbacklight: 100 %

xbacklight -set 50 ........worked faded to 50 % brightness.

so: with stock fedora, and pressing fn+f4 , xbacklight WORKS.
using quirk-reset-brightness, xbacklight doesn't work.
Comment 8 Carlo Raudino 2008-06-14 06:49:23 EDT
GREAT, kernel-2.6.26-0.67.rc6.git1  FIXES THIS PROBLEM!

I tried, and backlight is correctly resumed.

After, I tried the "stable" kernel, and backlight doesn't work (obviously) with
it. So kernel 2.6.26 has a working resume from suspend for brightness.

Let's wait this kernel, it takes fresh air to my netbook :)

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