[PATCH] PM / QoS: Fix default runtime_pm device resume latency

[Daniel Vetter]

On Tue, Oct 31, 2017 at 05:37:50PM +0200, Jani Nikula wrote:
> On Tue, 31 Oct 2017, Geert Uytterhoeven <geert at linux-m68k.org> wrote:
> > Hi Rafael, Tero,
> >
> > CC pinchartl, dri-devel
> 
> Cc: Marta, Martin
> 
> Our CI is hitting this too.

Should be ok again, we've locally reverted this patch. But a big chunk of
the pw runs overnight did hit it unfortunately :-(
-Daniel

> 
> BR,
> Jani.
> 
> >
> > On Tue, Oct 31, 2017 at 2:10 PM, Geert Uytterhoeven
> > <geert at linux-m68k.org> wrote:
> >> CC linux-renesas-soc
> >>
> >> On Tue, Oct 31, 2017 at 2:09 PM, Geert Uytterhoeven
> >> <geert at linux-m68k.org> wrote:
> >>> On Tue, Oct 31, 2017 at 12:27 AM, Rafael J. Wysocki <rjw at rjwysocki.net> wrote:
> >>>> On Monday, October 30, 2017 11:19:08 AM CET Rafael J. Wysocki wrote:
> >>>>> On Mon, Oct 30, 2017 at 8:10 AM, Tero Kristo <t-kristo at ti.com> wrote:
> >>>>> > The recent change to the PM QoS framework to introduce a proper
> >>>>> > no constraint value overlooked to handle the devices which don't
> >>>>> > implement PM QoS OPS. Runtime PM is one of the more severely
> >>>>> > impacted subsystems, failing every attempt to runtime suspend
> >>>>> > a device. This leads into some nasty second level issues like
> >>>>> > probe failures and increased power consumption among other things.
> >>>>>
> >>>>> Oh, that's bad.
> >>>>>
> >>>>> Sorry about breaking it and thanks for the fix!
> >>>>>
> >>>>> > Fix this by adding a proper return value for devices that don't
> >>>>> > implement PM QoS implicitly.
> >>>>> >
> >>>>> > Fixes: 0cc2b4e5a020 ("PM / QoS: Fix device resume latency PM QoS")
> >>>>> > Signed-off-by: Tero Kristo <t-kristo at ti.com>
> >>>>> > Cc: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> >>>>>
> >>>>> Applied.
> >>>>
> >>>> And pushed to Linus.
> >>>
> >>> I'm afraid it is not sufficient.
> >>>
> >>> Commit 0cc2b4e5a020fc7f ("PM / QoS: Fix device resume latency PM QoS")
> >>> introduced two issues on Renesas platforms:
> >>>  1. After boot up, many devices have changed their state from "suspended"
> >>>     to "active", according to /sys/kernel/debug/pm_genpd/pm_genpd_summary
> >>>     (comparing that file across boots is one of my standard tests).
> >>>     Interestingly, doing a system suspend/resume cycle restores their state
> >>>     to "suspended".
> >>>
> >>>  2. During system suspend, the following warning is printed on
> >>>     r8a7791/koelsch:
> >>>
> >>>         i2c-rcar e6530000.i2c: runtime PM trying to suspend device but
> >>> active child
> >
> >  3. I've just bisected a seemingly unrelated issue to the same commit.
> >     On Salvator-XS with R-Car H3, initialization of the rcar-du driver now
> >     takes more than 1 minute due to flip_done time outs, while it took 0.12s
> >     before:
> >
> >     [    3.015035] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
> >     [    3.021721] [drm] No driver support for vblank timestamp query.
> >     [   13.280738] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR*
> > [CRTC:58:crtc-3] flip_done timed out
> >     [   23.520707] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR*
> > [CRTC:58:crtc-3] flip_done timed out
> >     [   33.760708] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR*
> > [CRTC:58:crtc-3] flip_done timed out
> >     [   44.000755] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR*
> > [CRTC:58:crtc-3] flip_done timed out
> >     [   44.003597] Console: switching to colour frame buffer device 128x48
> >     [   54.240707] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR*
> > [CRTC:58:crtc-3] flip_done timed out
> >     [   64.480706] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR*
> > [CRTC:58:crtc-3] flip_done timed out
> >     [   64.544876] rcar-du feb00000.display: fb0:  frame buffer device
> >     [   64.552013] [drm] Initialized rcar-du 1.0.0 20130110 for
> > feb00000.display on minor 0
> >     [   64.559873] [drm] Device feb00000.display probed
> >
> >>> Commit 2a9a86d5c81389cd ("PM / QoS: Fix default runtime_pm device resume
> >>> latency") fixes the second issue, but not the first.
> >
> > ... nor the third.
> >
> >>> Reverting commits 2a9a86d5c81389cd ("PM / QoS: Fix default runtime_pm
> >>> device resume latency") and 0cc2b4e5a020fc7f ("PM / QoS: Fix device resume
> >>> latency PM QoS") fixes both.
> >
> > ... all three.
> >
> >>> Do you have a clue?
> >>> Thanks!
> 
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch