drm/i915/gem: Drop lru bumping on display unpinning

Simplify the frontbuffer unpin by removing the lock requirement. The LRU
bumping was primarily to protect the GTT from being evicted and from
frontbuffers being eagerly shrunk. Now we protect frontbuffers from the
shrinker, and we avoid accidentally evicting from the GTT, so the
benefit from bumping LRU is no more, and we can save more time by not.
Reported-and-tested-by: Matti Hämäläinen <ccr@tnsp.org>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2905
Fixes: c1793ba8 ("drm/i915: Add ww locking to pin_to_display_plane, v2.")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210119214336.1463-6-chris@chris-wilson.co.uk
(cherry picked from commit 14ca83ee)
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_display.c

@@ -2309,7 +2309,7 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
 		 */
 		ret = i915_vma_pin_fence(vma);
 		if (ret != 0 && INTEL_GEN(dev_priv) < 4) {
-			i915_gem_object_unpin_from_display_plane(vma);
+			i915_vma_unpin(vma);
 			vma = ERR_PTR(ret);
 			goto err;
 		}
@@ -2327,12 +2327,9 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
 
 void intel_unpin_fb_vma(struct i915_vma *vma, unsigned long flags)
 {
-	i915_gem_object_lock(vma->obj, NULL);
 	if (flags & PLANE_HAS_FENCE)
 		i915_vma_unpin_fence(vma);
-	i915_gem_object_unpin_from_display_plane(vma);
-	i915_gem_object_unlock(vma->obj);
-
+	i915_vma_unpin(vma);
 	i915_vma_put(vma);
 }
 

drivers/gpu/drm/i915/display/intel_overlay.c

@@ -359,7 +359,7 @@ static void intel_overlay_release_old_vma(struct intel_overlay *overlay)
 	intel_frontbuffer_flip_complete(overlay->i915,
 					INTEL_FRONTBUFFER_OVERLAY(overlay->crtc->pipe));
 
-	i915_gem_object_unpin_from_display_plane(vma);
+	i915_vma_unpin(vma);
 	i915_vma_put(vma);
 }
 
@@ -860,7 +860,7 @@ static int intel_overlay_do_put_image(struct intel_overlay *overlay,
 	return 0;
 
 out_unpin:
-	i915_gem_object_unpin_from_display_plane(vma);
+	i915_vma_unpin(vma);
 out_pin_section:
 	atomic_dec(&dev_priv->gpu_error.pending_fb_pin);
 

drivers/gpu/drm/i915/gem/i915_gem_domain.c

@@ -387,48 +387,6 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
 	return vma;
 }
 
-static void i915_gem_object_bump_inactive_ggtt(struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *i915 = to_i915(obj->base.dev);
-	struct i915_vma *vma;
-
-	if (list_empty(&obj->vma.list))
-		return;
-
-	mutex_lock(&i915->ggtt.vm.mutex);
-	spin_lock(&obj->vma.lock);
-	for_each_ggtt_vma(vma, obj) {
-		if (!drm_mm_node_allocated(&vma->node))
-			continue;
-
-		GEM_BUG_ON(vma->vm != &i915->ggtt.vm);
-		list_move_tail(&vma->vm_link, &vma->vm->bound_list);
-	}
-	spin_unlock(&obj->vma.lock);
-	mutex_unlock(&i915->ggtt.vm.mutex);
-
-	if (i915_gem_object_is_shrinkable(obj)) {
-		unsigned long flags;
-
-		spin_lock_irqsave(&i915->mm.obj_lock, flags);
-
-		if (obj->mm.madv == I915_MADV_WILLNEED &&
-		    !atomic_read(&obj->mm.shrink_pin))
-			list_move_tail(&obj->mm.link, &i915->mm.shrink_list);
-
-		spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
-	}
-}
-
-void
-i915_gem_object_unpin_from_display_plane(struct i915_vma *vma)
-{
-	/* Bump the LRU to try and avoid premature eviction whilst flipping  */
-	i915_gem_object_bump_inactive_ggtt(vma->obj);
-
-	i915_vma_unpin(vma);
-}
-
 /**
  * Moves a single object to the CPU read, and possibly write domain.
  * @obj: object to act on
@@ -569,9 +527,6 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 	else
 		err = i915_gem_object_set_to_cpu_domain(obj, write_domain);
 
-	/* And bump the LRU for this access */
-	i915_gem_object_bump_inactive_ggtt(obj);
-
 	i915_gem_object_unlock(obj);
 
 	if (write_domain)

drivers/gpu/drm/i915/gem/i915_gem_object.h

@@ -486,7 +486,6 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
 				     u32 alignment,
 				     const struct i915_ggtt_view *view,
 				     unsigned int flags);
-void i915_gem_object_unpin_from_display_plane(struct i915_vma *vma);
 
 void i915_gem_object_make_unshrinkable(struct drm_i915_gem_object *obj);
 void i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj);