On Fri, Jun 28, 2013 at 02:15:16PM +0200, Daniel Vetter wrote: > On Thu, Jun 27, 2013 at 05:05:44PM +0200, Petter Reinholdtsen wrote: > > [Daniel Vetter] > > > The buttons might do something fancy behind the scenes (kernel or > > > userspace), so can you please also check whether directly changing > > > the backlight values in /sys/class/backlight works correctly? > > > > There is full brightness when I set the value of max_brightness into > > the brightness file (as in 'echo 4882 > brightness'), and complete > > darkness when it is set to 0. This was using acpi_backlight=vendor. > > I suspect that mean the intel_backlight driver is working correctly, > > but am not sure if 0 is supposed to be completely dark or not. > > Ok, so the intel backlight actually seems to work here and we only have a > funny interaction between the acpi backlight and the intel backlight. I'll > drop your patch to invert the i915 backlight brightness again. > > > > acpi can't invert, and the different backlight drivers can affect > > > each another in funny ways. Which is way we have a clearly defined > > > priority order that userspace should use, and then _only_ touch the > > > selected backlight. ACPI wins over i915, so if the ACPI backlight is > > > broken (but the raw i915 backlight driver works) we need to > > > blacklist it. > > > > Right. I guess my findings above mean the hardware should be > > blacklisted (from acpi?). > > Sounds like. Please file a bug report against ACPI -> Video on > bugzilla.kernel.org. When you file that bug please add me and Jani Nikula to the cc list. We have a few other inverted brightness quirks all on similar machines. So this could all be due to the same strange interaction between drm/i915 and teh specific ACPI implementation on these machines. Thanks, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
