drm/i915: dynamic render p-state support for Sandy Bridge

Add an interrupt handler for switching graphics frequencies and handling
PM interrupts.  This should allow for increased performance when busy
and lower power consumption when idle.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 45 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index adf983f01dda..0dadc025b77b 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -397,11 +397,49 @@ static void notify_ring(struct drm_device *dev,
 		  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
 }
 
+static void gen6_pm_irq_handler(struct drm_device *dev)
+{
+	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
+	u8 new_delay = dev_priv->cur_delay;
+	u32 pm_iir;
+
+	pm_iir = I915_READ(GEN6_PMIIR);
+	if (!pm_iir)
+		return;
+
+	if (pm_iir & GEN6_PM_RP_UP_THRESHOLD) {
+		if (dev_priv->cur_delay != dev_priv->max_delay)
+			new_delay = dev_priv->cur_delay + 1;
+		if (new_delay > dev_priv->max_delay)
+			new_delay = dev_priv->max_delay;
+	} else if (pm_iir & (GEN6_PM_RP_DOWN_THRESHOLD | GEN6_PM_RP_DOWN_TIMEOUT)) {
+		if (dev_priv->cur_delay != dev_priv->min_delay)
+			new_delay = dev_priv->cur_delay - 1;
+		if (new_delay < dev_priv->min_delay) {
+			new_delay = dev_priv->min_delay;
+			I915_WRITE(GEN6_RP_INTERRUPT_LIMITS,
+				   I915_READ(GEN6_RP_INTERRUPT_LIMITS) |
+				   ((new_delay << 16) & 0x3f0000));
+		} else {
+			/* Make sure we continue to get down interrupts
+			 * until we hit the minimum frequency */
+			I915_WRITE(GEN6_RP_INTERRUPT_LIMITS,
+				   I915_READ(GEN6_RP_INTERRUPT_LIMITS) & ~0x3f0000);
+		}
+
+	}
+
+	gen6_set_rps(dev, new_delay);
+	dev_priv->cur_delay = new_delay;
+
+	I915_WRITE(GEN6_PMIIR, pm_iir);
+}
+
 static irqreturn_t ironlake_irq_handler(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
 	int ret = IRQ_NONE;
-	u32 de_iir, gt_iir, de_ier, pch_iir;
+	u32 de_iir, gt_iir, de_ier, pch_iir, pm_iir;
 	u32 hotplug_mask;
 	struct drm_i915_master_private *master_priv;
 	u32 bsd_usr_interrupt = GT_BSD_USER_INTERRUPT;
@@ -417,8 +455,10 @@ static irqreturn_t ironlake_irq_handler(struct drm_device *dev)
 	de_iir = I915_READ(DEIIR);
 	gt_iir = I915_READ(GTIIR);
 	pch_iir = I915_READ(SDEIIR);
+	pm_iir = I915_READ(GEN6_PMIIR);
 
-	if (de_iir == 0 && gt_iir == 0 && pch_iir == 0)
+	if (de_iir == 0 && gt_iir == 0 && pch_iir == 0 &&
+	    (!IS_GEN6(dev) || pm_iir == 0))
 		goto done;
 
 	if (HAS_PCH_CPT(dev))
@@ -470,6 +510,9 @@ static irqreturn_t ironlake_irq_handler(struct drm_device *dev)
 		i915_handle_rps_change(dev);
 	}
 
+	if (IS_GEN6(dev))
+		gen6_pm_irq_handler(dev);
+
 	/* should clear PCH hotplug event before clear CPU irq */
 	I915_WRITE(SDEIIR, pch_iir);
 	I915_WRITE(GTIIR, gt_iir);