On Wednesday, May 08, 2013 02:07:59 PM Sparhawk wrote: > Hi, I've been chatting with bcooksley at the KDE forums [1], and he/she > suggested that I post here with my question. > > I have a Dell XPS 17 L702X, running Kubuntu 13.04 (KDE 4.10.2). In the > update from 12.10 to 13.04, changing the brightness no longer works as > expected. I get the same results using the brightness keys (which shows > feedback with the OSD) or using xbacklight. > > When `/etc/default/grub` contains > GRUB_CMDLINE_LINUX_DEFAULT="acpi_backlight=vendor" > > `/sys/class/backlight/` contains `dell_backlight` and `intel_backlight`. > Pressing the brightness keys modifies the value in > `dell_backlight/brightness`, but does nothing to the display . However, > if I manually modify the values in `intel_backlight/brightness`, the > backlight changes as expected. > > OTOH, If I modify `/etc/default/grub` to contain > GRUB_CMDLINE_LINUX_DEFAULT="" > > `/sys/class/backlight/` now contains `acpi_video0`, `acpi_video1` and > `intel_backlight`. Now, the brightness keys modify > `acpi_video1/brightness`, and the display's brightness alters. > > Even though this does work somewhat, setting `acpi_backlight=vendor` in > Kubuntu 12.10 gave me more control over the backlight. For example, I > could reduce the backlight down to 0% and have the screen turn off. > Without this grub option, I can reduce `acpi_video1/brightness` to 0 > with the brightness keys, but the backlight is still on (dimly). Hence, > it seems that the ideal situation is for the brightness keys to modify > intel_backlight instead of acpi_video1. Is this possible? > > Cheers, and thanks in advance. > Sparhawk. > > [1] http://forum.kde.org/viewtopic.php?f=63&t=110984 Hi
There are a bunch of bug reports in bugs.kde.org about these kinds of issues, bugzilla is the right place to discuss these things, not the mailist :p I just wrote this small wiki page with some information about these issues: http://community.kde.org/Solid/PowerDevil/Brightness In summary brightness situation in Kernel sucks, There is no guarantee that 0 means "display turned off" (for that we should use DPMS) and in your case is probably the GPU driver deciding which file to modify, not us. _______________________________________________ Kde-hardware-devel mailing list [email protected] https://mail.kde.org/mailman/listinfo/kde-hardware-devel
