I would like to try to summarize the various issues as they appear to me
reading the comments. Unfortunately we now seem to have a whole
collection of similar but yet different problems in one huge bug and
maybe we could untangle it by splitting of separate bugs for those.
1. an inverted brightness control (as initially reported in the bug)
There has been a patch in 2.6.27-13.29 that, in theory, should address this
by
"ACPI: video: Fix reversed brightness behavior on ThinkPad SL series"
(lp#330200)
So, starting with the mentioned kernel, the values in the acpi brightness
control should get sorted
from small to large numbers.
2. No brightness control with the acpi brightness controls present.
This, as far as I know, affects only ThinkPad/Lenovo laptops and it should
be indicated by a dmesg
entry from thinkpad_acpi saying "standard ACPI backlight interface
available, not loading native
one...". For those, the workaround would be to use "options thinkpad_acpi
brightness_enable=1"
in a file in /etc/modprobe.d. Maybe we should make this the default, though
that should be tested
well, in order not to break yet some other machines.
3. No brightness control without the acpi controls present
The one case of that I saw was an acer and indeed there is a bug in
Intrepi'ds acer-wmi that
reverts the intended behavior (back off if no acpi support is there but
stay if there is).
4. Brightness control working through the acpi interface (echoing values to the
sysfs controls)
but not through the Desktop interface. Maybe because there have been
changes to prevent
multiple acpi devices from creating the same VID entry n sysfs. So that
could be a Desktop
issue.
I would propose to open new bugs for 2-4 and verify and keep tracking 1 here.
For 2, there seems to be a report open (lp#324061) and it would be best to
track that issue there. For 3, lp#333386 seems the one matching best but for 4
I did not find a report that sounded like it described that issue. Maybe
someone is more successful and could point others there or open a new report
for it.
Finally 1: is this still an issue with the latest -proposed kernel? If yes,
could you add the Laptop vendor and model as well as the output of "grep -r .
/proc/acpi/video" here?
--
The slider brightness Applet has value inverted after the last update
(2.6.27-11)
https://bugs.launchpad.net/bugs/311716
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