Re: [PATCH] drm/i915: Consolidate checks for engine stats availability

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>]

On 22/11/2017 12:37, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2017-11-22 12:05:18)
> > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> >
> > Sagar noticed the check can be consolidated between the engine stats
> > implementation and the PMU.
> >
> > My first choice was a static inline helper but that got into include
> > ordering mess quickly fast so I went with a macro instead. At some point
> > we should perhaps looking into taking out the non-ringubffer bits from
> > intel_ringbuffer.h into a new intel_engine.h or something.
> >
> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> > Suggested-by: Sagar Arun Kamble <sagar.a.kamble@xxxxxxxxx>
> > Cc: Sagar Arun Kamble <sagar.a.kamble@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/i915_pmu.c         | 9 ++-------
> >   drivers/gpu/drm/i915/intel_engine_cs.c  | 4 ++--
> >   drivers/gpu/drm/i915/intel_ringbuffer.h | 2 ++
> >   3 files changed, 6 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> > index 1071935bfa67..112243720ff3 100644
> > --- a/drivers/gpu/drm/i915/i915_pmu.c
> > +++ b/drivers/gpu/drm/i915/i915_pmu.c
> > @@ -90,11 +90,6 @@ static unsigned int event_enabled_bit(struct perf_event *event)
> >          return config_enabled_bit(event->attr.config);
> >   }
> >   
> > -static bool supports_busy_stats(struct drm_i915_private *i915)
> > -{
> > -       return INTEL_GEN(i915) >= 8;
> > -}
> > -
> >   static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
> >   {
> >          u64 enable;
> > @@ -124,7 +119,7 @@ static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
> >           * Also there is software busyness tracking available we do not
> >           * need the timer for I915_SAMPLE_BUSY counter.
> >           */
> > -       else if (supports_busy_stats(i915))
> > +       else if (intel_supports_engine_stats(i915))
> >                  enable &= ~BIT(I915_SAMPLE_BUSY);
> >   
> >          /*
> > @@ -463,7 +458,7 @@ static void i915_pmu_event_read(struct perf_event *event)
> >   
> >   static bool engine_needs_busy_stats(struct intel_engine_cs *engine)
> >   {
> > -       return supports_busy_stats(engine->i915) &&
> > +       return intel_supports_engine_stats(engine->i915) &&
> >                 (engine->pmu.enable & BIT(I915_SAMPLE_BUSY));
> >   }
> >   
> > diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> > index fede62daf3e1..d53680c08cb0 100644
> > --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> > @@ -1863,7 +1863,7 @@ int intel_enable_engine_stats(struct intel_engine_cs *engine)
> >   {
> >          unsigned long flags;
> >   
> > -       if (INTEL_GEN(engine->i915) < 8)
> > +       if (!intel_supports_engine_stats(engine->i915))
> >                  return -ENODEV;
> >   
> >          spin_lock_irqsave(&engine->stats.lock, flags);
> > @@ -1924,7 +1924,7 @@ void intel_disable_engine_stats(struct intel_engine_cs *engine)
> >   {
> >          unsigned long flags;
> >   
> > -       if (INTEL_GEN(engine->i915) < 8)
> > +       if (!intel_supports_engine_stats(engine->i915))
> >                  return;
> >   
> >          spin_lock_irqsave(&engine->stats.lock, flags);
> > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> > index 3bd30d011866..37a389ff031e 100644
> > --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> > @@ -1054,6 +1054,8 @@ static inline void intel_engine_context_out(struct intel_engine_cs *engine)
> >          spin_unlock_irqrestore(&engine->stats.lock, flags);
> >   }
> >   
> > +#define intel_supports_engine_stats(i915) (INTEL_GEN(i915) >= 8)
>
> Hmm, do we have an engine->flags for caps? Just thinking that would be
> more accurate than a gen test stuffed away in a header. So at present we
> have no engine->flags, but we do already have one bool needs_cmd_parser
> that could be pulled into an engine->flags. (Not sure if engine->caps is
> a good name if we are adding HW caps at a later point.)

I can do that sure, I mean I can't imagine the setting being actually 
per-engine (cmd parser also really isn't, no?), but at least it would 
have the benefit of avoiding the header ordering problems. I think at 
least, will see.

Will go with engine->flags, NEEDS_CMD_PARSER and SUPPORTS_STATS.

Regards,

Tvrtko
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