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(kref: &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