[Intel-gfx] [PATCH] drm/i915: Enable runtime pm

[Chris Wilson]

Quoting Paulo Zanoni (2017-11-16 20:45:26)
> Em Qui, 2017-11-16 às 20:24 +0200, David Weinehall escreveu:
> > On Wed, Nov 08, 2017 at 04:25:42PM +0200, David Weinehall wrote:
> > > On Tue, Nov 07, 2017 at 05:18:21PM +0100, Daniel Vetter wrote:
> > > > Now that we have CI, and that pm_rpm fully passes (I guess the
> > > > audio
> > > > folks have implemented proper runtime pm for snd-hda, hooray, pls
> > > > confirm) it's time to enable this again by default.
> > > > 
> > > > Real goal here is to have 1 configuration only that we fully
> > > > support,
> > > > instead of tons of different codes with every user/customer
> > > > tuning it
> > > > differently. And really, power stuff should work by default, and
> > > > should be enabled by everywhere where it is save to do so.
> > > > 
> > > > v2: Completely new commit message, a few years passed since v1
> > > > ...
> > > > 
> > > > Cc: Takashi Iwai <tiwai at suse.de>
> > > > Cc: Liam Girdwood <liam.r.girdwood at intel.com>
> > > > Cc: "Yang, Libin" <libin.yang at intel.com>
> > > > Cc: "Lin, Mengdong" <mengdong.lin at intel.com>
> > > > Cc: "Li, Jocelyn" <jocelyn.li at intel.com>
> > > > Cc: "Kaskinen, Tanu" <tanu.kaskinen at intel.com>
> > > > Cc: "Zanoni, Paulo R" <paulo.r.zanoni at intel.com>
> > > > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > > 
> > > lgtm,
> > > 
> > > Reviewed-by: David Weinehall <david.weinehall at linux.intel.com>
> > 
> > Been testing a bit; test results are a bit discouraging when it comes
> > to
> > idle power consumption.
> > 
> > Our nightly test suite logs idle power consumption before running any
> > tests, after running all tests, and then finally after running
> > powertop --auto-tune.
> > 
> > The before and after cases are similar with and without patch,
> > but not so for the auto-tune case.
> > 
> > Without this patch, powertop --auto-tune yields a massive improvement
> > (on NUC6i5 the power consumption drops with more than a factor of 3),
> > while with this patch the power consumption just drops with 10% or
> > so.
> 
> What happens if you keep the autosuspend delay to 10000?

The problem with the extra hpd triggering a render and flip still
remains, but less frequent.

Remove compiz + desktop manager from the picture and see if that cures
it. Then obviously you have to try each of the main desktop managers /
display servers to see which have good/bad behaviour (if my hunch is
correct). And if it does, we can't proceed with an aggressive default,
but will have to recommend that the display managers set it according to
their needs.
-Chris