open fbc on ironlake cause about 1 Watss power increase on bltk-office/player benchmark. It is linux kernel driver bug. The following patch can disable the fbc and recover power regression. > --- > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c > index 80745f8..029af7a 100644 > --- a/drivers/gpu/drm/i915/i915_drv.c > +++ b/drivers/gpu/drm/i915/i915_drv.c > @@ -150,7 +150,7 @@ static const struct intel_device_info intel_ironlake_d_info = { > > static const struct intel_device_info intel_ironlake_m_info = { > .gen = 5, .is_mobile = 1, > - .need_gfx_hws = 1, .has_fbc = 1, .has_rc6 = 1, .has_hotplug = 1, > + .need_gfx_hws = 1, .has_fbc = 0, .has_rc6 = 1, .has_hotplug = 1, > .has_bsd_ring = 1, > };
As FBC is disabled on ILK, yes we shouldn't be including it in its capabilities. I am interested in just where the current logic is failing. As you say it is a regression, and the hardware has always been broken, what triggered the regression?
bltk-office and bltk-player will trigger this. that use openoffice 3.0 and mplayer
I applied the patch to -fixes, but I'm leaving this bug open for the time being to see if there is anything else to fix in our FBC code paths.
I retested this using -fixes 4efe070896e1f7373c98a13713e659d1f5dee52a drm/i915: make the blitter report buffer modifications to the FBC unit has_fbc = 0has_fbc = 1 ---------------------- idle min 16.3 15.2 idle max 17.6 16.3 idle avg 16.94 15.67 office min 14.4 15.1 office max 23.9 28 office avg 15.57 17.33
FBC is turned off for relevant ILK platforms.
A patch referencing this bug report has been merged in Linux v3.0-rc1: commit c1a9f047638b27e481d097910604316b8a0d132b Author: Jesse Barnes <jbarnes@virtuousgeek.org> Date: Thu May 5 15:24:21 2011 -0700 drm/i915: add fbc enable flag, but disable by default
A patch referencing this bug report has been merged in Linux v3.1-rc1: commit 9ce9d0695d15da23ffe817516ba5d0b58caf8d05 Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Fri Jul 8 12:22:40 2011 +0100 drm/i915: Set persistent-mode for ILK/SNB framebuffer compression
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