DocBook/drm: Use a <variablelist> for vblank ioctls

    <title>VBlank event handling</title>

    <title>VBlank event handling</title>

    <para>

    <para>

      The DRM core exposes two vertical blank related ioctls:

      The DRM core exposes two vertical blank related ioctls:

      DRM_IOCTL_WAIT_VBLANK and DRM_IOCTL_MODESET_CTL.

      <variablelist>

<!--!Edrivers/char/drm/drm_irq.c-->

        <varlistentry>

    </para>

          <term>DRM_IOCTL_WAIT_VBLANK</term>

          <listitem>

            <para>

            <para>

      DRM_IOCTL_WAIT_VBLANK takes a struct drm_wait_vblank structure

              This takes a struct drm_wait_vblank structure as its argument,

      as its argument, and is used to block or request a signal when a

              and it is used to block or request a signal when a specified

      specified vblank event occurs.

              vblank event occurs.

            </para>

            </para>

          </listitem>

        </varlistentry>

        <varlistentry>

          <term>DRM_IOCTL_MODESET_CTL</term>

          <listitem>

            <para>

            <para>

      DRM_IOCTL_MODESET_CTL should be called by application level

              This should be called by application level drivers before and

      drivers before and after mode setting, since on many devices, the

              after mode setting, since on many devices the vertical blank

      vertical blank counter is reset at that time.  Internally,

              counter is reset at that time.  Internally, the DRM snapshots

      the DRM snapshots the last vblank count when the ioctl is called

              the last vblank count when the ioctl is called with the

      with the _DRM_PRE_MODESET command so that the counter won't go

              _DRM_PRE_MODESET command so that the counter won't go backwards

      backwards (which is dealt with when _DRM_POST_MODESET is used).

              (which is dealt with when _DRM_POST_MODESET is used).

            </para>

          </listitem>

        </varlistentry>

      </variablelist>

<!--!Edrivers/char/drm/drm_irq.c-->

    </para>

    </para>

    <para>

    <para>

      To support the functions above, the DRM core provides several

      To support the functions above, the DRM core provides several