regression in vaio cw backlight

[DeBø]

In my Sony Vaio Cw backlight brightness control worked fine in 11.10 and on 12.04 before some upgrade during the period 15-17 february. After that days, i cannot anymore change backlight.

Note:
In KDE i still can change it.
now as workaround i use: echo 35 > /sys/class/backlight/nv_backlight/brightness

lsb_release -rd
Description: Ubuntu precise (development branch)
Release: 12.04

cat /proc/version_signature
Linux version 3.3.0-030300rc3-generic (root@gomeisa) (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) ) #201202082335 SMP Thu Feb 9 04:36:53 UTC 2012

[DeBø (black-painkiller)]

Still present! It's a big regression for the users of this notebook!

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[DeBø (black-painkiller)]

additional infos:
from terminal:
echo 45 > /sys/class/backlight/nv_backlight/brightness
echo 45 > /sys/devices/virtual/backlight/sony/subsystem/nv_backlight/brightness
both change the brightness!

values range:
/sys/devices/virtual/backlight/sony/subsystem/sony/brightness is [0-7]
/sys/devices/virtual/backlight/sony/subsystem/nv_backlight/brightness is [0-100]

i can do:
echo 65 > /sys/devices/virtual/backlight/sony/subsystem/nv_backlight/brightness (BRIGHTNESS WORKS!!)
echo 7 > /sys/devices/virtual/backlight/sony/subsystem/sony/brightness (OSD MOVES!!, BRIGHTNESS DOESN'T CHANGE!!!)

pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 3
pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --get-brightness
i get: 3 so OSD CHANGES, BRIGHTNESS DOESN'T CHANGE!!!

if I do:
pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 9
Could not set the value of the backlight: writing '9' to /sys/devices/virtual/backlight/sony/brightness failed
 => beause /sony/brightness is [0-7] and 9 is too much (correct)

org.gnome.SettingsDaemon.Power.Screen.SetPercentage 15 (OSD WORKS, BRIGHTNESS DOESN'T CHANGE!!!)

while in a kde session:
org/kde/Solid/PowerManagement.setBrightness 15 (ALL WORK FINE!!!!)

hope this can be usefull!
thanks you