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
105