On Wed, 2014-02-19 at 21:20 -0500, Josh Boyer wrote: > We've had a rather weird report[1] of the brightness adjustments being > broken in a specific case with Thinkpad x220 hardware (SandyBridge > based). If you boot the machine with it in a dock and then undock, > the brightness adjustments do not work. That is with either the FN > keys or the GNOME brightness slider. On an (rather old) ThinkPad X41, which also uses i915, brightness adjustments stopped working altogether in v3.14-rc1 (I haven't used its docking station in the v3.14 release cycle). In v3.13.y things behave as expected. So perhaps there's actually a more general problem here. > I can see that the value of > /sys/class/backlight/acpi_video0/brightness On the X41 I check /proc/acpi/ibm/brightness ... > increases/decreases but > /sys/class/backlight/intel_backlight/brightness doesn't reflect any > changes. but otherwise things look similar. > With 3.12 this works, and oddly with 3.14-rc1 it works > (specifically, it starts working around v3.13-10231-g53d8ab2 which is > right after the first DRM merge for 3.14). With 3.13, if I undock and > echo a higher value in the intel_backlight_brightness sysfs entry, the > brightness will actually increase so it can be done manually, but it > does not work as you'd expect. Echoing values into /sys/class/backlight/intel_backlight/brightness works too (that's a new trick for me!). But, again, no docking station is required, so the problem looks less odd than the problem on that x220. > I'm in the middle of trying to do a reverse bisect for which patch > fixes it in the 3.14-rcX series, but that's taking a while. I thought > I'd email and see if anyone already knows about this situation, what > patch in 3.13 broke this, and which one then fixed it again. Thus far > all I've gathered is that backlight handling is confusing. I haven't yet tried bisecting. > [1] https://bugzilla.redhat.com/show_bug.cgi?id=1067071 Paul Bolle _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
