[Intel-gfx] [PATCH] drm/i915: Mask PM/RPS interrupt generation based on activity

[Daniel Vetter]

On Sun, Mar 30, 2014 at 12:08:35PM +0530, Deepak S wrote:
> 
> On Friday 28 March 2014 01:33 PM, Chris Wilson wrote:
> >The speculation is that we can conserve more power by masking off
> >the interrupts at source (PMINTRMSK) rather than filtering them by the
> >up/down thresholds (RPINTLIM). We can select which events we know will
> >be active based on the current frequency versus our imposed range, i.e.
> >if at minimum, we know we will not want to generate any more
> >down-interrupts and vice versa.
> >
> >v2: We only need the TIMEOUT when above min frequency.
> >v3: Tweak VLV at the same time
> >
> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >Cc: Deepak S <deepak.s at linux.intel.com>
> >---
> >I see your point that I cannot remove PMINTRMSK from enable_interrupts
> >without tweaking VLV at the same time. I did consider making this 4
> >patches (factor out gen6_rps_pm_mask, tweak gen6+, tweak, vlv, remove it
> >from enable_interrupts) but decided that was just being silly and
> >squashed the two patches together instead.
> >---
> >  drivers/gpu/drm/i915/intel_pm.c | 41 +++++++++++++++++++++++++----------------
> >  1 file changed, 25 insertions(+), 16 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> >index 154aa07d51a7..35a7b5b65883 100644
> >--- a/drivers/gpu/drm/i915/intel_pm.c
> >+++ b/drivers/gpu/drm/i915/intel_pm.c
> >@@ -3006,6 +3006,24 @@ static void gen6_set_rps_thresholds(struct drm_i915_private *dev_priv, u8 val)
> >  	dev_priv->rps.last_adj = 0;
> >  }
> >+static u32 gen6_rps_pm_mask(struct drm_i915_private *dev_priv, u8 val)
> >+{
> >+	u32 mask = 0;
> >+
> >+	if (val > dev_priv->rps.min_freq_softlimit)
> >+		mask |= GEN6_PM_RP_DOWN_THRESHOLD | GEN6_PM_RP_DOWN_TIMEOUT;
> >+	if (val < dev_priv->rps.max_freq_softlimit)
> >+		mask |= GEN6_PM_RP_UP_THRESHOLD;
> >+
> >+	/* IVB and SNB hard hangs on looping batchbuffer
> >+	 * if GEN6_PM_UP_EI_EXPIRED is masked.
> >+	 */
> >+	if (INTEL_INFO(dev_priv->dev)->gen <= 7 && !IS_HASWELL(dev_priv->dev))
> >+		mask |= GEN6_PM_RP_UP_EI_EXPIRED;
> >+
> >+	return ~mask;
> >+}
> >+
> >  /* gen6_set_rps is called to update the frequency request, but should also be
> >   * called when the range (min_delay and max_delay) is modified so that we can
> >   * update the GEN6_RP_INTERRUPT_LIMITS register accordingly. */
> >@@ -3037,6 +3055,7 @@ void gen6_set_rps(struct drm_device *dev, u8 val)
> >  	 * until we hit the minimum or maximum frequencies.
> >  	 */
> >  	I915_WRITE(GEN6_RP_INTERRUPT_LIMITS, gen6_rps_limits(dev_priv, val));
> >+	I915_WRITE(GEN6_PMINTRMSK, gen6_rps_pm_mask(dev_priv, val));
> >  	POSTING_READ(GEN6_RPNSWREQ);
> >@@ -3089,6 +3108,9 @@ static void vlv_set_rps_idle(struct drm_i915_private *dev_priv)
> >  	I915_WRITE(VLV_GTLC_SURVIVABILITY_REG,
> >  		I915_READ(VLV_GTLC_SURVIVABILITY_REG) &
> >  				~VLV_GFX_CLK_FORCE_ON_BIT);
> >+
> >+	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)
> >@@ -3134,13 +3156,12 @@ void valleyview_set_rps(struct drm_device *dev, u8 val)
> >  			 dev_priv->rps.cur_freq,
> >  			 vlv_gpu_freq(dev_priv, val), val);
> >-	if (val == dev_priv->rps.cur_freq)
> >-		return;
> >+	if (val != dev_priv->rps.cur_freq)
> >+		vlv_punit_write(dev_priv, PUNIT_REG_GPU_FREQ_REQ, val);
> >-	vlv_punit_write(dev_priv, PUNIT_REG_GPU_FREQ_REQ, val);
> >+	I915_WRITE(GEN6_PMINTRMSK, val);
> >  	dev_priv->rps.cur_freq = val;
> >-
> >  	trace_intel_gpu_freq_change(vlv_gpu_freq(dev_priv, val));
> >  }
> >@@ -3220,24 +3241,12 @@ int intel_enable_rc6(const struct drm_device *dev)
> >  static void gen6_enable_rps_interrupts(struct drm_device *dev)
> >  {
> >  	struct drm_i915_private *dev_priv = dev->dev_private;
> >-	u32 enabled_intrs;
> >  	spin_lock_irq(&dev_priv->irq_lock);
> >  	WARN_ON(dev_priv->rps.pm_iir);
> >  	snb_enable_pm_irq(dev_priv, dev_priv->pm_rps_events);
> >  	I915_WRITE(GEN6_PMIIR, dev_priv->pm_rps_events);
> >  	spin_unlock_irq(&dev_priv->irq_lock);
> >-
> >-	/* only unmask PM interrupts we need. Mask all others. */
> >-	enabled_intrs = dev_priv->pm_rps_events;
> >-
> >-	/* IVB and SNB hard hangs on looping batchbuffer
> >-	 * if GEN6_PM_UP_EI_EXPIRED is masked.
> >-	 */
> >-	if (INTEL_INFO(dev)->gen <= 7 && !IS_HASWELL(dev))
> >-		enabled_intrs |= GEN6_PM_RP_UP_EI_EXPIRED;
> >-
> >-	I915_WRITE(GEN6_PMINTRMSK, ~enabled_intrs);
> >  }
> >  static void gen8_enable_rps(struct drm_device *dev)
> 
> Reviewed-by:Deepak S <deepak.s at linux.intel.com>

All three patches merged, thanks. btw has this changed anything on the
negative effect of the boost logic you've seen on byt (iirc in video
workloads)?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch