drm/doc: Update plane documentation and add plane helper library

          pointer to CRTC functions.

        </para>

      </sect3>

      <sect3>

      <sect3 id="drm-kms-crtcops">

        <title>CRTC Operations</title>

        <sect4>

          <title>Set Configuration</title>

	optionally scale it to a destination size. The result is then blended

	with or overlayed on top of a CRTC.

      </para>

      <para>

      The DRM core recognizes three types of planes:

      <itemizedlist>

        <listitem>

        DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC.  Primary

        planes are the planes operated upon by by CRTC modesetting and flipping

        operations described in <xref linkend="drm-kms-crtcops"/>.

        </listitem>

        <listitem>

        DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC.  Cursor

        planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and

        DRM_IOCTL_MODE_CURSOR2 ioctls.

        </listitem>

        <listitem>

        DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes.

        Some drivers refer to these types of planes as "sprites" internally.

        </listitem>

      </itemizedlist>

      For compatibility with legacy userspace, only overlay planes are made

      available to userspace by default.  Userspace clients may set the

      DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that

      they wish to receive a universal plane list containing all plane types.

      </para>

      <sect3>

        <title>Plane Initialization</title>

        <para>

          Planes are optional. To create a plane, a KMS drivers allocates and

          To create a plane, a KMS drivers allocates and

          zeroes an instances of struct <structname>drm_plane</structname>

          (possibly as part of a larger structure) and registers it with a call

          to <function>drm_plane_init</function>. The function takes a bitmask

          to <function>drm_universal_plane_init</function>. The function takes a bitmask

          of the CRTCs that can be associated with the plane, a pointer to the

          plane functions and a list of format supported formats.

          plane functions, a list of format supported formats, and the type of

          plane (primary, cursor, or overlay) being initialized.

        </para>

        <para>

          Cursor and overlay planes are optional.  All drivers should provide

          one primary plane per CRTC (although this requirement may change in

          the future); drivers that do not wish to provide special handling for

          primary planes may make use of the helper functions described in

          <xref linkend="drm-kms-planehelpers"/> to create and register a

          primary plane with standard capabilities.

        </para>

      </sect3>

      <sect3>

  <sect1>

    <title>Mode Setting Helper Functions</title>

    <para>

      The CRTC, encoder and connector functions provided by the drivers

      The plane, CRTC, encoder and connector functions provided by the drivers

      implement the DRM API. They're called by the DRM core and ioctl handlers

      to handle device state changes and configuration request. As implementing

      those functions often requires logic not specific to drivers, mid-layer

    </para>

    <para>

      The DRM core contains one mid-layer implementation. The mid-layer provides

      implementations of several CRTC, encoder and connector functions (called

      from the top of the mid-layer) that pre-process requests and call

      implementations of several plane, CRTC, encoder and connector functions

      (called from the top of the mid-layer) that pre-process requests and call

      lower-level functions provided by the driver (at the bottom of the

      mid-layer). For instance, the

      <function>drm_crtc_helper_set_config</function> function can be used to

!Iinclude/linux/hdmi.h

!Edrivers/video/hdmi.c

    </sect2>

    <sect2>

      <title id="drm-kms-planehelpers">Plane Helper Reference</title>

!Edrivers/gpu/drm/drm_plane_helper.c Plane Helpers

    </sect2>

  </sect1>

  <!-- Internals: kms properties -->