I can confirm this works as well, however it disables _all_ power
management and makes the system run very hot as well as not suspending
to RAM/hibernating. --Not a desirable solution for a laptop. I will
try the latest upstream kernel to see if it helps with ACPI enabled.
Regards,
Larry
On Fri
Public bug reported:
By default whatever the brightness is set to upon power-up/reboot is what
Ubuntu will use from GRUB on into the X session.
Reading through https://wiki.ubuntu.com/Kernel/Debugging/Backlight I
disassembled the ACPI BIOS info (per
https://wiki.ubuntu.com/BIOSandUbuntu#Buggy%2
** Attachment added: "ACPI disassembly for Differentiated System Description
Table"
https://bugs.launchpad.net/bugs/741223/+attachment/1934200/+files/DSDT.dsl.bz2
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Thanks for the suggestions/info, I apologize for the delay in replying.
I noticed the delayed/ignored Fn keys for brightness/sound, but that
really isn't the problem. There is a disconnect in the kernel ACPI
interface between the value stored for the desired brightness and what
the hardware uses.
I tried using acpi_listen and the values for brightness are immediately updated
even though the OSD does not appear most of the time. Here's an example:
# acpi_listen &
[1] 27934
# while sleep 1 ; do cat
/sys/devices/pci:00/:00:02.0/backlight/acpi_video0/actual_brightness ;
done
4
video
