https://bugzilla.novell.com/show_bug.cgi?id=669798
https://bugzilla.novell.com/show_bug.cgi?id=669798#c20
Sean McNally changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |NEW
InfoProvider|Sean.D.McNally@GMail.com |
Summary|[i915, eDP] Kernel 2.6.39 |[i915, eDP] Kernels 2.6.39
|(was 2.6.38-rc3) regresses |et al (was 2.6.38-rc3)
|to black screen on boot |regresses to black screen
| |on boot
--- Comment #20 from Sean McNally 2011-10-20 13:07:12 UTC ---
Recent analysis of related efforts starting with
http://http://comments.gmane.org/gmane.linux.kernel/1192955 and
http://http://comments.gmane.org/gmane.linux.kernel/1090610 led to discovering
the following:
Display brightness could be managed via:
$ echo nn > /sys/class/backlight/acpi_video0
where "nn" is an integer between 0 and 20
However, this should have been reflected in /sys/class/backlight/acer-wmi,
where acer-wmi represents the vendor supplied -acpi BIOS interface.
Addition of "acpi_backlight=vendor" to the kernel boot options provides
rectification of the "black screen" at boot-time, as well as "black screen"
experienced during power-management actions, such as "suspend" and "hibernate",
as well as screen dimming.
Addition of "acpi_backlight=vendor" modifies /sys/class/backlight/acpi_video0
to /sys/class/backlight/acer-wmi, providing kernel interface to the acer-wmi
BIOS support.
Tested on 11.4, kernels 2.6.37.6 and 3.1.0-rc9-7, both Gnome (2.32) and KDE
(4.7.2).
Tested on 12.1MS5++ (basically 12.1 updated to factory), kernels 3.0.0-4 and
3.1.0-rc9-7, with Gnome 3 and KDE (4.7.2). (Gnome 3 incorrectly sets
brightness low at resume, but this is a Gnome 3 problem, not a kernel issue).
Testing hardware: Gateway NV79, Intel i5-430M (aka "Arrandale"), with Intel
GMA HD (aka "Ironlake") graphics, 4GB. Testing only in 64-bit (x86-64) real
mode. No VM involvement used in any testing.
Further, keyboard-managed screen brightness (fn+up/down arrows) functioned
correctly, and brightness levels maintained across logoff/login, as well as
across suspend/resume and hibernate/resume.
COMMENT: This issue is based on the "backlight" management, partially attained
at kernel 2.6.38-rc1/2, and regressed.
Bug title amended to reflect continuance to present release and factory
kernels.
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