drm/i915: Drop unpin stall in atomic_prepare_commit

The core already does this in setup_commit(). With this we can also
remove the unpin_work_count since it's the last user, and also remove
the loop since that was only used for stalling against legacy flips.

v2: Amend commit message a bit (Chris).

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20170720175754.30751-8-daniel.vetter@ffwll.ch

drivers/gpu/drm/i915/intel_display.c

@@ -11815,18 +11815,7 @@ static int intel_atomic_check(struct drm_device *dev,
 static int intel_atomic_prepare_commit(struct drm_device *dev,
 				       struct drm_atomic_state *state)
 {
-	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct drm_crtc_state *crtc_state;
-	struct drm_crtc *crtc;
-	int i, ret;
-
-	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
-		if (state->legacy_cursor_update)
-			continue;
-
-		if (atomic_read(&to_intel_crtc(crtc)->unpin_work_count) >= 2)
-			flush_workqueue(dev_priv->wq);
-	}
+	int ret;
 
 	ret = mutex_lock_interruptible(&dev->struct_mutex);
 	if (ret)

drivers/gpu/drm/i915/intel_drv.h

@@ -798,8 +798,6 @@ struct intel_crtc {
 	unsigned long long enabled_power_domains;
 	struct intel_overlay *overlay;
 
-	atomic_t unpin_work_count;
-
 	/* Display surface base address adjustement for pageflips. Note that on
 	 * gen4+ this only adjusts up to a tile, offsets within a tile are
 	 * handled in the hw itself (with the TILEOFF register). */