DocBook/drm: Refer to the domain-setting function as a device-specific ioctl

	has finished rendering to the object, then the object must be made

	coherent with the CPU's view

	of memory, usually involving GPU cache flushing of various kinds.

	This core CPU<->GPU coherency management is provided by the GEM

	set domain function, which evaluates an object's current domain and

	This core CPU<->GPU coherency management is provided by a

	device-specific ioctl, which evaluates an object's current domain and

	performs any necessary flushing or synchronization to put the object

	into the desired coherency domain (note that the object may be busy,

	i.e. an active render target; in that case, the set domain function

	i.e. an active render target; in that case, setting the domain

	blocks the client and waits for rendering to complete before

	performing any necessary flushing operations).

      </para>