[just moving from lkml to intel-gfx for a better fitting audience] On Mon, 25 Aug 2014, Jani Nikula <jani.nikula@xxxxxxxxx> wrote: > On Fri, 22 Aug 2014, Eric Rannaud <eric.rannaud@xxxxxxxxx> wrote: >> Hi, >> >> Between 3.15.4 and 3.15.8, there was an increase in idle power consumption on >> Apple Macbook Pro 15 (late 2013) on a freshly booted system (no wifi driver >> loaded; brightness set to 4/100; X running; no desktop environment, except >> Awesome), from 6.5W to about 10.5W, as reported by powertop. >> >> In the stable tree, it bisects to: >> commit f4db98240ac2c6d9d2118c6f82d483ff5293f1ed >> Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> Date: Fri Jun 6 10:37:11 2014 +0100 >> >> drm/i915: Disable FBC by default also on Haswell and later >> >> commit 0368920e51ae0cded0eb518c340a4dd17764d461 upstream. >> >> It causes black screen on bootup and is approximately 100x >> slower than >> running with FBC disabled, so the GPU runs at a high >> frequency for much >> longer - completely contrary to the power saving claims. >> It also still >> has mutex deadlocks in multi-head scenarios, which can lead to a >> system/X lockup. These bugs were known before FBC was >> enabled by default >> on Haswell and still have not been fixed. >> >> The issue is still present in Linus' tree (v3.17-rc1-22-g480cadc2b7e0). >> >> With a 75Wh battery, that's a significant loss in battery life in normal use. >> >> I'll be happy to help test any potential fix. > > The earlier regression trumps, and in this case it was enabling FBC by > default on Haswell. Sorry. > > You can enable FBC with i915.enable_fbc=1 module parameter, but all bets > are off. See the commit message you quoted above. I don't recommend. > > BR, > Jani. > > > -- > Jani Nikula, Intel Open Source Technology Center -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
