drm/doc: diagram for mode objects and properties

Modeset Base Object Abstraction

===============================

.. kernel-render:: DOT

   :alt: Mode Objects and Properties

   :caption: Mode Objects and Properties

   digraph {

      node [shape=box]

      "drm_property A" -> "drm_mode_object A"

      "drm_property A" -> "drm_mode_object B"

      "drm_property B" -> "drm_mode_object A"

   }

The base structure for all KMS objects is :c:type:`struct drm_mode_object

<drm_mode_object>`. One of the base services it provides is tracking properties,

which are especially important for the atomic IOCTL (see `Atomic Mode

Setting`_). The somewhat surprising part here is that properties are not

directly instantiated on each object, but free-standing mode objects themselves,

represented by :c:type:`struct drm_property <drm_property>`, which only specify

the type and value range of a property. Any given property can be attached

multiple times to different objects using :c:func:`drm_object_attach_property()

<drm_object_attach_property>`.

.. kernel-doc:: include/drm/drm_mode_object.h

   :internal: