drivers/gpu/drm/i915/gem/i915_gem_object_frontbuffer.h

   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
  15 void __i915_gem_object_flush_frontbuffer(struct drm_i915_gem_object *obj,
  16                                          enum fb_op_origin origin);
  17 void __i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj,
  18                                               enum fb_op_origin origin);
  19
  20 static inline void
  21 i915_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
  28 static inline void
  29 i915_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  */
  45 static inline struct intel_frontbuffer *
  46 i915_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  */
  84 static inline struct intel_frontbuffer *
  85 i915_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         } else if (rcu_access_pointer(obj->frontbuffer)) {
  93                 cur = rcu_dereference_protected(obj->frontbuffer, true);
  94                 kref_get(&cur->ref);
  95         } else {
  96                 drm_gem_object_get(intel_bo_to_drm_bo(obj));
  97                 rcu_assign_pointer(obj->frontbuffer, front);
  98         }
  99
 100         return cur;
 101 }
 102
 103 #endif