drm/gem: Update/Polish docs

A bunch of things have been removed meanwhile and docs not fully
brought up to speed. And a few gaps closed where I noticed missing
kerneldoc while reading through the overview sections.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445533889-7661-3-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Documentation/DocBook/gpu.tmpl

@@ -615,18 +615,6 @@ char *date;</synopsis>
           <function>drm_gem_object_init</function>. Storage for private GEM
           objects must be managed by drivers.
         </para>
-        <para>
-          Drivers that do not need to extend GEM objects with private information
-          can call the <function>drm_gem_object_alloc</function> function to
-          allocate and initialize a struct <structname>drm_gem_object</structname>
-          instance. The GEM core will call the optional driver
-          <methodname>gem_init_object</methodname> operation after initializing
-          the GEM object with <function>drm_gem_object_init</function>.
-          <synopsis>int (*gem_init_object) (struct drm_gem_object *obj);</synopsis>
-        </para>
-        <para>
-          No alloc-and-init function exists for private GEM objects.
-        </para>
       </sect3>
       <sect3>
         <title>GEM Objects Lifetime</title>
@@ -649,15 +637,9 @@ char *date;</synopsis>
         </para>
         <para>
           <synopsis>void (*gem_free_object) (struct drm_gem_object *obj);</synopsis>
-          Drivers are responsible for freeing all GEM object resources, including
+          Drivers are responsible for freeing all GEM object resources. This includes
-          the resources created by the GEM core. If an mmap offset has been
+          the resources created by the GEM core, which need to be released with
-          created for the object (in which case
+          <function>drm_gem_object_release</function>.
-          <structname>drm_gem_object</structname>::<structfield>map_list</structfield>::<structfield>map</structfield>
-          is not NULL) it must be freed by a call to
-          <function>drm_gem_free_mmap_offset</function>. The shmfs backing store
-          must be released by calling <function>drm_gem_object_release</function>
-          (that function can safely be called if no shmfs backing store has been
-          created).
         </para>
       </sect3>
       <sect3>
@@ -740,17 +722,10 @@ char *date;</synopsis>
           DRM identifies the GEM object to be mapped by a fake offset passed
           through the mmap offset argument. Prior to being mapped, a GEM object
           must thus be associated with a fake offset. To do so, drivers must call
-          <function>drm_gem_create_mmap_offset</function> on the object. The
+          <function>drm_gem_create_mmap_offset</function> on the object.
-          function allocates a fake offset range from a pool and stores the
-          offset divided by PAGE_SIZE in
-          <literal>obj-&gt;map_list.hash.key</literal>. Care must be taken not to
-          call <function>drm_gem_create_mmap_offset</function> if a fake offset
-          has already been allocated for the object. This can be tested by
-          <literal>obj-&gt;map_list.map</literal> being non-NULL.
         </para>
         <para>
           Once allocated, the fake offset value
-          (<literal>obj-&gt;map_list.hash.key &lt;&lt; PAGE_SHIFT</literal>)
           must be passed to the application in a driver-specific way and can then
           be used as the mmap offset argument.
         </para>

drivers/gpu/drm/drm_gem.c

@@ -244,8 +244,9 @@ drm_gem_object_handle_unreference_unlocked(struct drm_gem_object *obj)
  * @filp: drm file-private structure to use for the handle look up
  * @handle: userspace handle to delete
  *
- * Removes the GEM handle from the @filp lookup table and if this is the last
+ * Removes the GEM handle from the @filp lookup table which has been added with
- * handle also cleans up linked resources like GEM names.
+ * drm_gem_handle_create(). If this is the last handle also cleans up linked
+ * resources like GEM names.
  */
 int
 drm_gem_handle_delete(struct drm_file *filp, u32 handle)
@@ -314,6 +315,10 @@ EXPORT_SYMBOL(drm_gem_dumb_destroy);
  * This expects the dev->object_name_lock to be held already and will drop it
  * before returning. Used to avoid races in establishing new handles when
  * importing an object from either an flink name or a dma-buf.
+ *
+ * Handles must be release again through drm_gem_handle_delete(). This is done
+ * when userspace closes @file_priv for all attached handles, or through the
+ * GEM_CLOSE ioctl for individual handles.
  */
 int
 drm_gem_handle_create_tail(struct drm_file *file_priv,
@@ -541,7 +546,17 @@ void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
 }
 EXPORT_SYMBOL(drm_gem_put_pages);
 
-/** Returns a reference to the object named by the handle. */
+/**
+ * drm_gem_object_lookup - look up a GEM object from it's handle
+ * @dev: DRM device
+ * @filp: DRM file private date
+ * @handle: userspace handle
+ *
+ * Returns:
+ *
+ * A reference to the object named by the handle if such exists on @filp, NULL
+ * otherwise.
+ */
 struct drm_gem_object *
 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,
 		      u32 handle)
@@ -774,6 +789,13 @@ drm_gem_object_free(struct kref *kref)
 }
 EXPORT_SYMBOL(drm_gem_object_free);
 
+/**
+ * drm_gem_vm_open - vma->ops->open implementation for GEM
+ * @vma: VM area structure
+ *
+ * This function implements the #vm_operations_struct open() callback for GEM
+ * drivers. This must be used together with drm_gem_vm_close().
+ */
 void drm_gem_vm_open(struct vm_area_struct *vma)
 {
 	struct drm_gem_object *obj = vma->vm_private_data;
@@ -782,6 +804,13 @@ void drm_gem_vm_open(struct vm_area_struct *vma)
 }
 EXPORT_SYMBOL(drm_gem_vm_open);
 
+/**
+ * drm_gem_vm_close - vma->ops->close implementation for GEM
+ * @vma: VM area structure
+ *
+ * This function implements the #vm_operations_struct close() callback for GEM
+ * drivers. This must be used together with drm_gem_vm_open().
+ */
 void drm_gem_vm_close(struct vm_area_struct *vma)
 {
 	struct drm_gem_object *obj = vma->vm_private_data;