Comment 0 for bug 139954

Binary package hint: xserver-xorg-video-intel

Sony laptop doesn't use standard acpi brightness so it isn't possible to change brightness with the brightness keys without sony-laptop module and the acpi-support script sonybright.sh. The brightness line of power management settings have no effect.
Sony-laptop has two sys values to change brightness. One for the current brightness (/sys/class/backlight/sony/brightness) and one (/sys/devices/platform/sony-laptop/brightness_default) for the brightness after restart or resume from suspend. Atm the default value isn't changed automatically which is reported at https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.22/+bug/117331 but this is no problem since it is possible to change brightness_default value as root. To test this I have set both (current and default) to zero.
If I use new Intel driver the tft shows the highest brightness after gdm start but the sys brightness values haven't changed. If I press brightness increase key (decrease isn't possible because the lowest value is already used) brightness jumps from highest to the second lowest mode which is correct according to sys values but not according to real brightness. This isn't so hard but the same brightness reset to highest mode happens if I start a video (at least under compiz with xv) .
If I set both brightness values to 7 (the highest mode) I see no change of brightness after video play, logout or restart so Intel driver always resets to highest mode.
This doesn't happen with i810 driver so this seems to be a driver issue.
I am using a Sony Vaio TX2 Laptop with latest Gutsy.