https://bugzilla.kernel.org/show_bug.cgi?id=51141
URL: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=69236
1
Summary: ACPI display backlight brightness is set to zero at
every boot-up
Product: ACPI
Version: 2.5
Kernel Version: 3.6.8
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: Other
AssignedTo: acpi_ot...@kernel-bugs.osdl.org
ReportedBy: pub...@stefan-nagy.at
Regression: No
Created an attachment (id=87851)
--> (https://bugzilla.kernel.org/attachment.cgi?id=87851)
dmesg log (kernel 3.6.8)
Every time I boot-up my notebook's display stays black. Since most of the time
I'm using an external display I found out that the backlight brightness in
GNOME settings is set to zero – I can temporarily solve the issue by increasing
the screen brightness but next time I boot this setting is lost, screen
brightness is set back to zero again. Using the kernel boot parameter
i915.invert_brightness=1 works fine as workaround.
When I looked into /sys/class/backlight/acpi_video0/brightness to confirm that
it's set to zero I realized that I have two entries in backlight:
- 'acpi_video0' (with brightness set to 0, actual_brightness set to 0) and
- 'intel_backlight' (with brightness set to 4882, actual_brightness set to 0).
When I increase screen brightness to 100% in GNOME settings, the values change
to:
- 'acpi_video0' brightness & actual_brightness 10,
- 'intel_backlight' brightness & actual_brightness 4882.
Next time I boot, ACPI display backlight brightness is set to 0 again.
I'm affected by this bug since kernel v3.6, before that I was affected by Bug
#46481. My notebook is a HP Folio 13-200, I'll attach a dmesg-log and the
output of acpidump.
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