drm/i915: FBC doesn't need struct_mutex anymore

Everything is covered either by fbc.lock or mm.stolen_lock, and
intel_fbc.c is already responsible for grabbing the appropriate locks
when it needs them.

Reviewed-by: Chris wilson <chris@chris-wilson.co.uk>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8ddeb29..eb50f59 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4747,11 +4747,8 @@
 	if (crtc->atomic.update_wm_post)
 		intel_update_watermarks(&crtc->base);
 
-	if (atomic->update_fbc) {
-		mutex_lock(&dev->struct_mutex);
+	if (atomic->update_fbc)
 		intel_fbc_update(dev);
-		mutex_unlock(&dev->struct_mutex);
-	}
 
 	if (atomic->post_enable_primary)
 		intel_post_enable_primary(&crtc->base);
@@ -4783,11 +4780,8 @@
 	if (atomic->wait_for_flips)
 		intel_crtc_wait_for_pending_flips(&crtc->base);
 
-	if (atomic->disable_fbc) {
-		mutex_lock(&dev->struct_mutex);
+	if (atomic->disable_fbc)
 		intel_fbc_disable_crtc(crtc);
-		mutex_unlock(&dev->struct_mutex);
-	}
 
 	if (crtc->atomic.disable_ips)
 		hsw_disable_ips(crtc);
@@ -11473,9 +11467,9 @@
 
 	i915_gem_track_fb(intel_fb_obj(work->old_fb), obj,
 			  to_intel_plane(primary)->frontbuffer_bit);
+	mutex_unlock(&dev->struct_mutex);
 
 	intel_fbc_disable(dev);
-	mutex_unlock(&dev->struct_mutex);
 	intel_frontbuffer_flip_prepare(dev,
 				       to_intel_plane(primary)->frontbuffer_bit);
 
@@ -15605,9 +15599,7 @@
 
 	intel_unregister_dsm_handler();
 
-	mutex_lock(&dev->struct_mutex);
 	intel_fbc_disable(dev);
-	mutex_unlock(&dev->struct_mutex);
 
 	/* flush any delayed tasks or pending work */
 	flush_scheduled_work();