On Thu, Apr 01, 2021 at 10:38:11AM +0100, Tvrtko Ursulin wrote:
>
> On 01/04/2021 10:19, Rodrigo Vivi wrote:
> > On Wed, Mar 31, 2021 at 11:18:50AM +0100, Tvrtko Ursulin wrote:
> > > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> > >
> > > RC6 support cannot be simply established by looking at the static device
> > > HAS_RC6() flag. There are cases which disable RC6 at driver load time so
> > > use the status of those check when deciding whether to enumerate the rc6
> > > counter.
> > >
> > > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> > > Reported-by: Eero T Tamminen <eero.t.tamminen@xxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/i915/i915_pmu.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> > > index 41651ac255fa..a75cd1db320b 100644
> > > --- a/drivers/gpu/drm/i915/i915_pmu.c
> > > +++ b/drivers/gpu/drm/i915/i915_pmu.c
> > > @@ -476,6 +476,8 @@ engine_event_status(struct intel_engine_cs *engine,
> > > static int
> > > config_status(struct drm_i915_private *i915, u64 config)
> > > {
> > > + struct intel_gt *gt = &i915->gt;
> > > +
> > > switch (config) {
> > > case I915_PMU_ACTUAL_FREQUENCY:
> > > if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
> > > @@ -489,7 +491,7 @@ config_status(struct drm_i915_private *i915, u64 config)
> > > case I915_PMU_INTERRUPTS:
> > > break;
> > > case I915_PMU_RC6_RESIDENCY:
> > > - if (!HAS_RC6(i915))
> > > + if (!gt->rc6.supported)
> >
> > Is this really going to remove any confusion?
> > Right now it is there but with residency 0, but after this change the event is
> > not there anymore so I wonder if we are not just changing to a different kind
> > of confusion on users.
>
> I think it is possible to argue both ways.
>
> 1)
> HAS_RC6 means hardware has RC6 so if we view PMU as very low level we can
> say always export it.
>
> If i915 had to turn it off (rc6->supported == false) due firmware or GVT-g,
> then we could say reporting zero RC6 is accurate in that sense. Only the
> reason "why it is zero" is missing for PMU users.
>
> 2)
> Or if we go with this patch we could say that presence of the PMU metric
> means RC6 is active and enabled, while absence means it is either not
> supported due platform (or firmware) or how the platform is getting used
> (GVT-g).
>
yeap, these 2 cases described well my mental conflict...
> So I think patch is a bit better. I don't see it is adding more confusion.
As I said on the other patch I have no strong position on which is better,
but if you and Eero feel that this works better for the current case,
let's do it...
>
> >
> > > return -ENODEV;
> >
> > would a different return help somehow?
>
> Like distinguishing between not theoretically possible to support on this
> GPU, versus not active? Perhaps.. suggest an errno? :)
ENODATA? or EIDRM?
But only if it helps somehow... otherwise don't bother and move with
this as is:
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>
> Regards,
>
> Tvrtko
>
> >
> > > break;
> > > case I915_PMU_SOFTWARE_GT_AWAKE_TIME:
> > > --
> > > 2.27.0
> > >
> > > _______________________________________________
> > > Intel-gfx mailing list
> > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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