Re: [RFC][PATCH 2/2] drm/i915: Jump to at least RPe on VLV when increasing the GPU frequency

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jun 25, 2013 at 11:54:39AM -0700, Jesse Barnes wrote:
> On Tue, 25 Jun 2013 21:38:11 +0300
> ville.syrjala@linux.intel.com wrote:
> 
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > If the current GPU frquency is below RPe, and we're asked to increase
> > it, just go directly to RPe. This should provide better performance
> > faster than letting the frequency trickle up in response to the up
> > threshold interrupts.
> > 
> > For now just do it for VLV, since that matches quite closely how VLV
> > used to operate when the rps delayed timer kept things at RPe always.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_irq.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 62f8b2d..d6bd0d7 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -699,9 +699,17 @@ static void gen6_pm_rps_work(struct work_struct *work)
> >  
> >  	mutex_lock(&dev_priv->rps.hw_lock);
> >  
> > -	if (pm_iir & GEN6_PM_RP_UP_THRESHOLD)
> > +	if (pm_iir & GEN6_PM_RP_UP_THRESHOLD) {
> >  		new_delay = dev_priv->rps.cur_delay + 1;
> > -	else
> > +
> > +		/*
> > +		 * For better performance, jump directly
> > +		 * to RPe if we're below it.
> > +		 */
> > +		if (IS_VALLEYVIEW(dev_priv->dev) &&
> > +		    dev_priv->rps.cur_delay < dev_priv->rps.rpe_delay)
> > +			new_delay = dev_priv->rps.rpe_delay;
> > +	} else
> >  		new_delay = dev_priv->rps.cur_delay - 1;
> >  
> >  	/* sysfs frequency interfaces may have snuck in while servicing the
> 
> Yeah, seems reasonable.  Going to RP1 on other platforms might be a
> good approximation of this.
> 
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Queued for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch