On Wed, Sep 25, 2013 at 08:18:39PM +0300, Jani Nikula wrote: > On Wed, 25 Sep 2013, Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> wrote: > > Still digging up the actual VBT info for this, but wanted to get this > > out there for testing, or in case others are also bugged by this. > > I had a look at this a few weeks back. The VBT value for max backlight > is in Hz (as is the value you get through opregion) and transforming > that into the value the registers eat needs some digging. I tried, but > none of the real world examples of VBT and PWM freq matched any of that, > so I moved on... > > > This can happen if you boot with an external display connected. In that > > case, the attached eDP backlight modulation frequency may not be > > programmed, so we need to use something (in this case the value my BIOS > > normally programs with just the internal display enabled). > > Something similar is required for non-vlv ChromeOS stuff too AFAIK. Afaik ChromeOS doesn't have a vbt, so I think we need to shovel some failsafe (yeah, failsafe and backlight doesn't compute, I know) default into the regs in case all else fails. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
