1/* SPDX-License-Identifier: MIT */
  2/*
  3 * Copyright © 2023 Intel Corporation
  4 */
  5
  6#ifndef __I915_GEM_OBJECT_FRONTBUFFER_H__
  7#define __I915_GEM_OBJECT_FRONTBUFFER_H__
  8
  9#include <linux/kref.h>
 10#include <linux/rcupdate.h>
 11
 12#include "display/intel_frontbuffer.h"
 13#include "i915_gem_object_types.h"
 14
 15void __i915_gem_object_flush_frontbuffer(struct drm_i915_gem_object *obj,
 16					 enum fb_op_origin origin);
 17void __i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj,
 18					      enum fb_op_origin origin);
 19
 20static inline void
 21i915_gem_object_flush_frontbuffer(struct drm_i915_gem_object *obj,
 22				  enum fb_op_origin origin)
 23{
 24	if (unlikely(rcu_access_pointer(obj->frontbuffer)))
 25		__i915_gem_object_flush_frontbuffer(obj, origin);
 26}
 27
 28static inline void
 29i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj,
 30				       enum fb_op_origin origin)
 31{
 32	if (unlikely(rcu_access_pointer(obj->frontbuffer)))
 33		__i915_gem_object_invalidate_frontbuffer(obj, origin);
 34}
 35
 36/**
 37 * i915_gem_object_get_frontbuffer - Get the object's frontbuffer
 38 * @obj: The object whose frontbuffer to get.
 39 *
 40 * Get pointer to object's frontbuffer if such exists. Please note that RCU
 41 * mechanism is used to handle e.g. ongoing removal of frontbuffer pointer.
 42 *
 43 * Return: pointer to object's frontbuffer is such exists or NULL
 44 */
 45static inline struct intel_frontbuffer *
 46i915_gem_object_get_frontbuffer(const struct drm_i915_gem_object *obj)
 47{
 48	struct intel_frontbuffer *front;
 49
 50	if (likely(!rcu_access_pointer(obj->frontbuffer)))
 51		return NULL;
 52
 53	rcu_read_lock();
 54	do {
 55		front = rcu_dereference(obj->frontbuffer);
 56		if (!front)
 57			break;
 58
 59		if (unlikely(!kref_get_unless_zero(&front->ref)))
 60			continue;
 61
 62		if (likely(front == rcu_access_pointer(obj->frontbuffer)))
 63			break;
 64
 65		intel_frontbuffer_put(front);
 66	} while (1);
 67	rcu_read_unlock();
 68
 69	return front;
 70}
 71
 72/**
 73 * i915_gem_object_set_frontbuffer - Set the object's frontbuffer
 74 * @obj: The object whose frontbuffer to set.
 75 * @front: The frontbuffer to set
 76 *
 77 * Set object's frontbuffer pointer. If frontbuffer is already set for the
 78 * object keep it and return it's pointer to the caller. Please note that RCU
 79 * mechanism is used to handle e.g. ongoing removal of frontbuffer pointer. This
 80 * function is protected by i915->display.fb_tracking.lock
 81 *
 82 * Return: pointer to frontbuffer which was set.
 83 */
 84static inline struct intel_frontbuffer *
 85i915_gem_object_set_frontbuffer(struct drm_i915_gem_object *obj,
 86				struct intel_frontbuffer *front)
 87{
 88	struct intel_frontbuffer *cur = front;
 89
 90	if (!front) {
 91		RCU_INIT_POINTER(obj->frontbuffer, NULL);
 92		drm_gem_object_put(intel_bo_to_drm_bo(obj));
 93	} else if (rcu_access_pointer(obj->frontbuffer)) {
 94		cur = rcu_dereference_protected(obj->frontbuffer, true);
 95		kref_get(&cur->ref);
 96	} else {
 97		drm_gem_object_get(intel_bo_to_drm_bo(obj));
 98		rcu_assign_pointer(obj->frontbuffer, front);
 99	}
100
101	return cur;
102}
103
104#endif