On Sat, 29 Dec 2007, Ben Liblit wrote: > > Eh? actual_brightness is changing but the *display* backlight level (not the > > value of any sysfs files, the actual screen brightness) is not changing? > > Yes, that's exactly what's happening. Weird, isn't it? Indeed. > To create the simplest test environment possible, I booted into > single-user mode. So no HAL, no X, nothing but the basics. My findings: Thanks. > The brightness keys change the physical screen as expected at the GRUB > boot prompt. Good. > The brightness keys change the value reported by actual_brightness but > do not actually change the physical screen once the machine is booted > and running Linux in single-user mode. I tried all four values (0-3) of > brightness_mode, and they all behave the same in this regard. Which means something is updating both the NVRAM and the EC (which it is *NOT* supposed to be updated in a X61!!!! fortunately, it is a no-op, and not something that would cause further misbehaviour). Those are the sources of the values thinkpad-acpi uses to report actual_brightness. > actual_brightness changes but the physical screen does not. Echoing my > own value into brightness works: it changes both actual_brightness and > the physical screen. So the thinkpad-acpi code to *change* brightness is working. But something else, either in thinkpad-acpi or elsewhere, is not doing the job properly. Do you have the ACPI video.c driver loaded, perchance? Also, make sure acpid is not loaded (thinkpad-acpi doesn't need it, and something in userspace might be hooked to it). > This is also what happens if the thinkpad_acpi module has been hidden > from view and therefore never loaded into the kernel at all. Of course > I cannot view actual_brightness in this case, but I can say that the > brightness keys have no affect on the actual brightness of the physical > screen. Hmm, this *could* be a BIOS bug, but that would be a seriously weird one, unless X.org was loaded beforehand (it can mess with something in the GPU registers which tells the BIOS to hands off changing the display brightness directly). -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ ibm-acpi-devel mailing list ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/ibm-acpi-devel
