acquired and release by <function>calling drm_gem_object_reference</function>
and <function>drm_gem_object_unreference</function> respectively. The
caller must hold the <structname>drm_device</structname>
- <structfield>struct_mutex</structfield> lock. As a convenience, GEM
- provides the <function>drm_gem_object_reference_unlocked</function> and
- <function>drm_gem_object_unreference_unlocked</function> functions that
- can be called without holding the lock.
+ <structfield>struct_mutex</structfield> lock when calling
+ <function>drm_gem_object_reference</function>. As a convenience, GEM
+ provides <function>drm_gem_object_unreference_unlocked</function>
+ functions that can be called without holding the lock.
</para>
<para>
When the last reference to a GEM object is released the GEM core calls
abstracted from the client in libdrm.
</para>
</sect3>
- <sect3>
- <title>GEM Function Reference</title>
+ </sect2>
+ <sect2>
+ <title>GEM Function Reference</title>
!Edrivers/gpu/drm/drm_gem.c
- </sect3>
+!Iinclude/drm/drm_gem.h
</sect2>
<sect2>
<title>VMA Offset Manager</title>
*/
/**
- * This structure defines the drm_mm memory object, which will be used by the
- * DRM for its buffer objects.
+ * struct drm_gem_object - GEM buffer object
+ *
+ * This structure defines the generic parts for GEM buffer objects, which are
+ * mostly around handling mmap and userspace handles.
+ *
+ * Buffer objects are often abbreviated to BO.
*/
struct drm_gem_object {
- /** Reference count of this object */
+ /**
+ * @refcount:
+ *
+ * Reference count of this object
+ *
+ * Please use drm_gem_object_reference() to acquire and
+ * drm_gem_object_unreference() or drm_gem_object_unreference_unlocked()
+ * to release a reference to a GEM buffer object.
+ */
struct kref refcount;
/**
- * handle_count - gem file_priv handle count of this object
+ * @handle_count:
+ *
+ * This is the GEM file_priv handle count of this object.
*
* Each handle also holds a reference. Note that when the handle_count
* drops to 0 any global names (e.g. the id in the flink namespace) will
* be cleared.
*
* Protected by dev->object_name_lock.
- * */
+ */
unsigned handle_count;
- /** Related drm device */
+ /**
+ * @dev: DRM dev this object belongs to.
+ */
struct drm_device *dev;
- /** File representing the shmem storage */
+ /**
+ * @filp:
+ *
+ * SHMEM file node used as backing storage for swappable buffer objects.
+ * GEM also supports driver private objects with driver-specific backing
+ * storage (contiguous CMA memory, special reserved blocks). In this
+ * case @filp is NULL.
+ */
struct file *filp;
- /* Mapping info for this object */
+ /**
+ * @vma_node:
+ *
+ * Mapping info for this object to support mmap. Drivers are supposed to
+ * allocate the mmap offset using drm_gem_create_mmap_offset(). The
+ * offset itself can be retrieved using drm_vma_node_offset_addr().
+ *
+ * Memory mapping itself is handled by drm_gem_mmap(), which also checks
+ * that userspace is allowed to access the object.
+ */
struct drm_vma_offset_node vma_node;
/**
+ * @size:
+ *
* Size of the object, in bytes. Immutable over the object's
* lifetime.
*/
size_t size;
/**
+ * @name:
+ *
* Global name for this object, starts at 1. 0 means unnamed.
- * Access is covered by the object_name_lock in the related drm_device
+ * Access is covered by dev->object_name_lock. This is used by the GEM_FLINK
+ * and GEM_OPEN ioctls.
*/
int name;
/**
- * Memory domains. These monitor which caches contain read/write data
+ * @read_domains:
+ *
+ * Read memory domains. These monitor which caches contain read/write data
* related to the object. When transitioning from one set of domains
* to another, the driver is called to ensure that caches are suitably
- * flushed and invalidated
+ * flushed and invalidated.
*/
uint32_t read_domains;
+
+ /**
+ * @write_domain: Corresponding unique write memory domain.
+ */
uint32_t write_domain;
/**
+ * @pending_read_domains:
+ *
* While validating an exec operation, the
* new read/write domain values are computed here.
* They will be transferred to the above values
* at the point that any cache flushing occurs
*/
uint32_t pending_read_domains;
+
+ /**
+ * @pending_write_domain: Write domain similar to @pending_read_domains.
+ */
uint32_t pending_write_domain;
/**
- * dma_buf - dma buf associated with this GEM object
+ * @dma_buf:
+ *
+ * dma-buf associated with this GEM object.
*
* Pointer to the dma-buf associated with this gem object (either
* through importing or exporting). We break the resulting reference
* loop when the last gem handle for this object is released.
*
- * Protected by obj->object_name_lock
+ * Protected by obj->object_name_lock.
*/
struct dma_buf *dma_buf;
/**
- * import_attach - dma buf attachment backing this object
+ * @import_attach:
+ *
+ * dma-buf attachment backing this object.
*
* Any foreign dma_buf imported as a gem object has this set to the
* attachment point for the device. This is invariant over the lifetime
struct vm_area_struct *vma);
int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
+/**
+ * drm_gem_object_reference - acquire a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This acquires additional reference to @obj. It is illegal to call this
+ * without already holding a reference. No locks required.
+ */
static inline void
drm_gem_object_reference(struct drm_gem_object *obj)
{
kref_get(&obj->refcount);
}
+/**
+ * drm_gem_object_unreference - release a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This releases a reference to @obj. Callers must hold the dev->struct_mutex
+ * lock when calling this function, even when the driver doesn't use
+ * dev->struct_mutex for anything.
+ *
+ * For drivers not encumbered with legacy locking use
+ * drm_gem_object_unreference_unlocked() instead.
+ */
static inline void
drm_gem_object_unreference(struct drm_gem_object *obj)
{
}
}
+/**
+ * drm_gem_object_unreference_unlocked - release a GEM BO reference
+ * @obj: GEM buffer object
+ *
+ * This releases a reference to @obj. Callers must not hold the
+ * dev->struct_mutex lock when calling this function.
+ */
static inline void
drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
{
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