drm/i915: rip our vblank reset hacks for runtime PM

Now that we unconditionally dtrt when disabling/enabling crtcs we
don't need any hacks any longer to keep the vblank logic sane when
all the registers go poof. So let's rip it all out.

This essentially undoes

commit 9dbd8febb4dbc9199fcf340b882eb930e36b65b6
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date:   Tue Jul 23 10:48:11 2013 -0300

    drm/i915: update last_vblank when disabling the power well

Apparently igt/kms_flip is already powerful enough to exercise this
properly, yay! See the reference regression report for details.

v2: Update testcase name

References: https://bugs.freedesktop.org/show_bug.cgi?id=66808
Testcase: igt/kms_flip/vblank-vs-*-rpm
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -5545,33 +5545,6 @@ static void hsw_power_well_post_enable(struct drm_i915_private *dev_priv)
 	}
 }
 
-static void reset_vblank_counter(struct drm_device *dev, enum pipe pipe)
-{
-	assert_spin_locked(&dev->vbl_lock);
-
-	dev->vblank[pipe].last = 0;
-}
-
-static void hsw_power_well_post_disable(struct drm_i915_private *dev_priv)
-{
-	struct drm_device *dev = dev_priv->dev;
-	enum pipe pipe;
-	unsigned long irqflags;
-
-	/*
-	 * After this, the registers on the pipes that are part of the power
-	 * well will become zero, so we have to adjust our counters according to
-	 * that.
-	 *
-	 * FIXME: Should we do this in general in drm_vblank_post_modeset?
-	 */
-	spin_lock_irqsave(&dev->vbl_lock, irqflags);
-	for_each_pipe(pipe)
-		if (pipe != PIPE_A)
-			reset_vblank_counter(dev, pipe);
-	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
-}
-
 static void hsw_set_power_well(struct drm_i915_private *dev_priv,
 			       struct i915_power_well *power_well, bool enable)
 {
@@ -5600,8 +5573,6 @@ static void hsw_set_power_well(struct drm_i915_private *dev_priv,
 			I915_WRITE(HSW_PWR_WELL_DRIVER, 0);
 			POSTING_READ(HSW_PWR_WELL_DRIVER);
 			DRM_DEBUG_KMS("Requesting to disable the power well\n");
-
-			hsw_power_well_post_disable(dev_priv);
 		}
 	}
 }
@@ -5770,11 +5741,6 @@ static void vlv_display_power_well_disable(struct drm_i915_private *dev_priv,
 	valleyview_disable_display_irqs(dev_priv);
 	spin_unlock_irq(&dev_priv->irq_lock);
 
-	spin_lock_irq(&dev->vbl_lock);
-	for_each_pipe(pipe)
-		reset_vblank_counter(dev, pipe);
-	spin_unlock_irq(&dev->vbl_lock);
-
 	vlv_set_power_well(dev_priv, power_well, false);
 }