[PATCH] drm/i915: pin sprite fb only if it changed

[Gustavo Padovan <gustavo@padovan.org>]

From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

Optimize code avoiding helding dev mutex if old fb and current fb
are the same.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
---
 drivers/gpu/drm/i915/intel_sprite.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index a4306cf..a301838 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -1038,21 +1038,23 @@ intel_commit_sprite_plane(struct drm_plane *plane,
 	primary_enabled = !drm_rect_equals(dst, clip) || colorkey_enabled(intel_plane);
 	WARN_ON(!primary_enabled && !state->visible && intel_crtc->active);
 
-	mutex_lock(&dev->struct_mutex);
 
 	/* Note that this will apply the VT-d workaround for scanouts,
 	 * which is more restrictive than required for sprites. (The
 	 * primary plane requires 256KiB alignment with 64 PTE padding,
 	 * the sprite planes only require 128KiB alignment and 32 PTE padding.
 	 */
-	ret = intel_pin_and_fence_fb_obj(dev, obj, NULL);
+	if (old_obj != obj) {
+		mutex_lock(&dev->struct_mutex);
+		ret = intel_pin_and_fence_fb_obj(dev, obj, NULL);
 
-	i915_gem_track_fb(old_obj, obj,
-			  INTEL_FRONTBUFFER_SPRITE(pipe));
-	mutex_unlock(&dev->struct_mutex);
+		i915_gem_track_fb(old_obj, obj,
+				  INTEL_FRONTBUFFER_SPRITE(pipe));
+		mutex_unlock(&dev->struct_mutex);
 
-	if (ret)
-		return ret;
+		if (ret)
+			return ret;
+	}
 
 	intel_plane->crtc_x = state->orig_dst.x1;
 	intel_plane->crtc_y = state->orig_dst.y1;
@@ -1098,15 +1100,18 @@ intel_commit_sprite_plane(struct drm_plane *plane,
 			intel_post_enable_primary(crtc);
 	}
 
+	if (!old_obj)
+		return 0;
+
 	/* Unpin old obj after new one is active to avoid ugliness */
-	if (old_obj) {
+	if (old_obj != obj) {
 		/*
 		 * It's fairly common to simply update the position of
 		 * an existing object.  In that case, we don't need to
 		 * wait for vblank to avoid ugliness, we only need to
 		 * do the pin & ref bookkeeping.
 		 */
-		if (old_obj != obj && intel_crtc->active)
+		if (intel_crtc->active)
 			intel_wait_for_vblank(dev, intel_crtc->pipe);
 
 		mutex_lock(&dev->struct_mutex);
-- 
1.9.3