Re: [PATCH] drm/i915: Remove wait for for punit to updates freq.

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Remove wait for for punit to updates freq.
Date: Tue, 28 Apr 2015 21:32:43 +0300	[thread overview]
Message-ID: <20150428183243.GP18908@intel.com> (raw)
In-Reply-To: <553FCE7D.6090806@virtuousgeek.org>

On Tue, Apr 28, 2015 at 11:16:29AM -0700, Jesse Barnes wrote:
> On 03/04/2015 08:08 PM, deepak.s@linux.intel.com wrote:
> > From: Deepak S <deepak.s@linux.intel.com>
> > 
> > When GPU is idle on VLV, Request freq to punit should be good enough to
> > get the voltage back to VNN. Also, make sure gfx clock force applies
> > before requesting the freq fot vlv.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75244
> > suggested-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> > Signed-off-by: Deepak S <deepak.s@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 20 ++++----------------
> >  1 file changed, 4 insertions(+), 16 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index e710b43..2e1ed07 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -3894,7 +3894,7 @@ static void valleyview_set_rps(struct drm_device *dev, u8 val)
> >   * * If Gfx is Idle, then
> >   * 1. Mask Turbo interrupts
> >   * 2. Bring up Gfx clock
> > - * 3. Change the freq to Rpn and wait till P-Unit updates freq
> > + * 3. Request the freq to Rpn.
> >   * 4. Clear the Force GFX CLK ON bit so that Gfx can down
> >   * 5. Unmask Turbo interrupts
> >  */
> > @@ -3902,8 +3902,8 @@ static void vlv_set_rps_idle(struct drm_i915_private *dev_priv)
> >  {
> >  	struct drm_device *dev = dev_priv->dev;
> >  
> > -	/* CHV and latest VLV don't need to force the gfx clock */
> > -	if (IS_CHERRYVIEW(dev) || dev->pdev->revision >= 0xd) {
> > +	/* CHV don't need to force the gfx clock */
> > +	if (IS_CHERRYVIEW(dev)) {
> >  		valleyview_set_rps(dev_priv->dev, dev_priv->rps.min_freq_softlimit);
> >  		return;
> >  	}
> > @@ -3920,20 +3920,8 @@ static void vlv_set_rps_idle(struct drm_i915_private *dev_priv)
> >  		   gen6_sanitize_rps_pm_mask(dev_priv, ~0));
> >  
> >  	vlv_force_gfx_clock(dev_priv, true);
> > -
> > -	dev_priv->rps.cur_freq = dev_priv->rps.min_freq_softlimit;
> > -
> > -	vlv_punit_write(dev_priv, PUNIT_REG_GPU_FREQ_REQ,
> > -					dev_priv->rps.min_freq_softlimit);
> > -
> > -	if (wait_for(((vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS))
> > -				& GENFREQSTATUS) == 0, 100))
> > -		DRM_ERROR("timed out waiting for Punit\n");
> > -
> > +	valleyview_set_rps(dev_priv->dev, dev_priv->rps.min_freq_softlimit);
> >  	vlv_force_gfx_clock(dev_priv, false);
> > -
> > -	I915_WRITE(GEN6_PMINTRMSK,
> > -		   gen6_rps_pm_mask(dev_priv, dev_priv->rps.cur_freq));
> >  }
> >  
> >  void gen6_rps_idle(struct drm_i915_private *dev_priv)
> > 
> 
> Yeah I think this is fine (may need a rebase though, you can keep my r-b
> if you do that in case Jani doesn't want to deal with the merge conflicts).
> 
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

The removal of the stepping check is still confusing me even if the
rest would be OK.

-- 
Ville Syrjälä
Intel OTC
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