Re: [PATCH 4/4] drm/i915: Use czclk_freq in vlv c0 residency calculations

[Daniel Vetter <daniel@ffwll.ch>]

Pulled in entire series, thanks.
-Daniel

On Tue, Sep 29, 2015 at 12:46:20AM +0300, Imre Deak wrote:
> On Mon, 2015-09-28 at 23:47 +0300, Imre Deak wrote:
> > On Thu, 2015-09-24 at 23:29 +0300, ville.syrjala@linux.intel.com wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > Replace the use of mem_freq/4 with czclk_freq in the vlv c0 residency
> > > calculations.
> > > 
> > > Also deal with VLV_COUNT_RANGE_HIGH which affects all RCx residency
> > > counters. We have just enough bits to do this without intermediate
> > > divisions.
> > > 
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_irq.c | 8 ++++++--
> > >  1 file changed, 6 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > > index 07c87e0..d78ef64 100644
> > > --- a/drivers/gpu/drm/i915/i915_irq.c
> > > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > > @@ -998,12 +998,16 @@ static bool vlv_c0_above(struct drm_i915_private *dev_priv,
> > >  			 int threshold)
> > >  {
> > >  	u64 time, c0;
> > > +	unsigned int mul = 100;
> > >  
> > >  	if (old->cz_clock == 0)
> > >  		return false;
> > >  
> > > +	if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)
> > > +		mul <<= 8;
> > 
> > Could've been a separate patch.
> > 
> > > +
> > >  	time = now->cz_clock - old->cz_clock;
> > > -	time *= threshold * dev_priv->mem_freq;
> > > +	time *= threshold * dev_priv->czclk_freq;
> > 
> > Not introduced in this patch, but the above doesn't look correct to me.
> > Time is cycles _divided_ by frequency, so imo the above should be either
> > a division, or better we should calculate c0 (10ns) cycles here.
> > 
> > >  
> > >  	/* Workload can be split between render + media, e.g. SwapBuffers
> > >  	 * being blitted in X after being rendered in mesa. To account for
> > > @@ -1011,7 +1015,7 @@ static bool vlv_c0_above(struct drm_i915_private *dev_priv,
> > >  	 */
> > >  	c0 = now->render_c0 - old->render_c0;
> > >  	c0 += now->media_c0 - old->media_c0;
> > > -	c0 *= 100 * VLV_CZ_CLOCK_TO_MILLI_SEC * 4 / 1000;
> > > +	c0 *= mul * VLV_CZ_CLOCK_TO_MILLI_SEC;
> > 
> > Based on the above this would need to be fixed too.
> 
> Nvm the above, I realized now how it works:) I was confused seeing that
> we scale by czclk freq and the 10ns freq the "opposite" time value.
> Sorry for the noise.
> 
> > The above can be done as a follow-up if needed; this patch does what it
> > says, so:
> > Reviewed-by: Imre Deak <imre.deak@intel.com>
> > 
> > >  
> > >  	return c0 >= time;
> > >  }
> > 
> > 
> > _______________________________________________
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> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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