Red Hat Bugzilla – Bug 426916
Lenovo T61 Display Brightness Set to Maxium after Suspend/Resume
Last modified: 2015-03-04 20:19:34 EST
Description of problem:
When a Lenovo T61 is suspended with Fn+F4 and resumed, the brightness of the
internal display is set to its maximum value. Enabling the reset_brightness
quirk does not solve this.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Set the display brightness to a low value with the Power Management
2. Suspend the laptop with Fn+F4.
3. Wake it up with the power button.
The display brightness is at its maximum.
The brightness should be the same as before the suspend/resume cycle.
to enable the reset_brightness quirk:
<match key="system.hardware.product" prefix="6464">
<merge key="power_management.quirk.s3_bios" type="bool">true</merge>
<merge key="power_management.quirk.vbemode_restore" type="bool">true</merge>
<merge key="power_management.quirk.reset_brightness" type="bool">true</merge>
This did not work.
The next thing I tried was to modify /usr/lib/pm-utils/sleep.d/99video,
replacing the reset_brightness function with a script:
The script is attached, and basically does the same as the original
reset_brightness function. But it sleeps 1 second before modifying
/sys/class/backlight/thinkpad_screen/brightness. This solved the problem.
The output of
lshal | grep system.hardware
system.hardware.primary_video.product = 10754 (0x2a02) (int)
system.hardware.primary_video.vendor = 32902 (0x8086) (int)
system.hardware.product = '6464Y1G' (string)
system.hardware.serial = 'L3C5908' (string)
system.hardware.uuid = 'A122A181-494A-11CB-A4F5-B04BA82A6D2D' (string)
system.hardware.vendor = 'LENOVO' (string)
system.hardware.version = 'ThinkPad T61' (string)
Created attachment 290487 [details]
script for resetting display brightness on Lenovo T61
Can you test, whether the brightness is also at maximum after you closed the lid
and opened it again without suspending?
Yes, the brightness is also at maximum after closing and opening the lid,
Also, the Fn keys for lowering and raising the brightness don't work. They
display an OSD widget with a changing indicator bar, but brightness is always
set to maximum.
The only way to lower the brightness are echos to /sys or /proc/acpi/ibm, and
the Gnome applet.
With the two latest kernels (kernel-18.104.22.168-12.fc8 and kernel-22.214.171.124-34.fc8),
the brightness cannot be controlled at all.
Instead of /sys/class/backlight/thinkpad_screen/brightness, I now have
/sys/class/backlight/acpi_video0/brightness. An echo to the new file takes about
one second to complete. While the content of the brightness file changes, the
actual brightness does not. The Gnome applet also has stopped working.
With the latest kernel-126.96.36.199-50.fc8, gnome-brightness-applet has started to
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