Am Mittwoch, den 15.08.2012, 10:41 +0200 schrieb Daniel Vetter: > James Bottomley reported [1] a massive power regression, due to the > enabling of semaphores by default in 3.5. A workaround for him is to > again disable semaphores. And indeed, his system has a very hard time > to entre rc6 with semaphores enabled. s,entre,enter, > Ben Widawsky run around with a kill-a-watt a lot and noticed: > - There are indeed a few rare systems that seem to have a hard time > entering rc6 when desktop-idle. > - One machine, The Indestructible Toshiba regressed in this behaviour Never heard that Toshiba name. > between 3.5 and 3.6 in a merge commit! So rc6 behaviour with the > current setting seems to be highly timing dependent and not robust > at all. > - The behaviour James reported wrt semaphores seems to be a freak > timing thing that only happens on his specific machine, confirming > that enabling semaphores shouldn't reduce rc6 residency. > > Now furthermore the Google ChromeOS guys reported [2] a while ago that > at least on some machines a simply a blinking cursor can keep the gpu > turbo at the highest frequency. This is because the current rps limits > used on snb/ivb are highly asymmetric. > > On the theory that gpu turbo and rc6 tuning values are related, we've > tried whether the much saner looking (since much less asymmetric) rps > tuning values used for hsw would also help entering rc6 more robustly. > > And it seems to work. > > Reference[1]: http://lists.freedesktop.org/archives/dri-devel/2012-July/025675.html > Reference[2]: http://lists.freedesktop.org/archives/intel-gfx/2012-July/018692.html > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=53393 > Tested-by: Ben Widawsky <ben at bwidawsk.net> Did James already confirm, that this fixes his problem? > Cc: stable at vger.kernel.org > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch> > --- > drivers/gpu/drm/i915/intel_pm.c | 15 ++++----------- > 1 file changed, 4 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c > index d64dffb..cf10a1d 100644 > --- a/drivers/gpu/drm/i915/intel_pm.c > +++ b/drivers/gpu/drm/i915/intel_pm.c > @@ -2482,17 +2482,10 @@ static void gen6_enable_rps(struct drm_device *dev) > dev_priv->rps.max_delay << 24 | > dev_priv->rps.min_delay << 16); > > - if (IS_HASWELL(dev)) { > - I915_WRITE(GEN6_RP_UP_THRESHOLD, 59400); > - I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 245000); > - I915_WRITE(GEN6_RP_UP_EI, 66000); > - I915_WRITE(GEN6_RP_DOWN_EI, 350000); > - } else { > - I915_WRITE(GEN6_RP_UP_THRESHOLD, 10000); > - I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 1000000); > - I915_WRITE(GEN6_RP_UP_EI, 100000); > - I915_WRITE(GEN6_RP_DOWN_EI, 5000000); > - } > + I915_WRITE(GEN6_RP_UP_THRESHOLD, 59400); > + I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 245000); > + I915_WRITE(GEN6_RP_UP_EI, 66000); > + I915_WRITE(GEN6_RP_DOWN_EI, 350000); > > I915_WRITE(GEN6_RP_IDLE_HYSTERSIS, 10); > I915_WRITE(GEN6_RP_CONTROL, Acked-by: Paul Menzel <paulepanter at users.sourceforge.net> Thanks, Paul -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: This is a digitally signed message part URL: <http://lists.freedesktop.org/archives/intel-gfx/attachments/20120815/43c0afd9/attachment.pgp>
