1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index f895d1508df8..b0e4a0bd1313 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5063,8 +5063,26 @@ static void __intel_set_power_well(struct drm_device *dev, bool enable)
                 }
         } else {
                 if (enable_requested) {
+                        unsigned long irqflags;
+                        enum pipe p;
+
                         I915_WRITE(HSW_PWR_WELL_DRIVER, 0);
+                        POSTING_READ(HSW_PWR_WELL_DRIVER);
                         DRM_DEBUG_KMS("Requesting to disable the power well\n");
+
+                        /*
+                         * 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(p)
+                                if (p != PIPE_A)
+                                        dev->last_vblank[p] = 0;
+                        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
                 }
         }
 }