drm/i915: Always update RPS interrupts thresholds along with frequency

In order to avoid missed down-interrupts when coming out of RC6, it is
advised that we always reset the down-threshold upon a PM event. This is
due to that the PM unit goes through a little dance when coming out of
RC6, it first brings the GPU up at the lowest frequency then a short
time later it restores the thresholds. During that interval, the
down-interval may expire and the interrupt be suppressed.

Now aware of the dance taking place within the GPU when coming out of
RC6, one wonders what other writes need to be queued in the fifo buffer
in order to be properly sequenced; setting the RP state appears to be
one.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44006
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 7 insertions, 30 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index cc4a633..1417660 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -350,8 +350,8 @@ static void gen6_pm_rps_work(struct work_struct *work)
 {
 	drm_i915_private_t *dev_priv = container_of(work, drm_i915_private_t,
 						    rps_work);
-	u8 new_delay = dev_priv->cur_delay;
 	u32 pm_iir, pm_imr;
+	u8 new_delay;
 
 	spin_lock_irq(&dev_priv->rps_lock);
 	pm_iir = dev_priv->pm_iir;
@@ -360,41 +360,18 @@ static void gen6_pm_rps_work(struct work_struct *work)
 	I915_WRITE(GEN6_PMIMR, 0);
 	spin_unlock_irq(&dev_priv->rps_lock);
 
-	if (!pm_iir)
+	if ((pm_iir & GEN6_PM_DEFERRED_EVENTS) == 0)
 		return;
 
 	mutex_lock(&dev_priv->dev->struct_mutex);
-	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)) {
-		gen6_gt_force_wake_get(dev_priv);
-		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_gt_force_wake_put(dev_priv);
-	}
+
+	if (pm_iir & GEN6_PM_RP_UP_THRESHOLD)
+		new_delay = dev_priv->cur_delay + 1;
+	else
+		new_delay = dev_priv->cur_delay - 1;
 
 	gen6_set_rps(dev_priv->dev, new_delay);
-	dev_priv->cur_delay = new_delay;
 
-	/*
-	 * rps_lock not held here because clearing is non-destructive. There is
-	 * an *extremely* unlikely race with gen6_rps_enable() that is prevented
-	 * by holding struct_mutex for the duration of the write.
-	 */
 	mutex_unlock(&dev_priv->dev->struct_mutex);
 }