DocBook/drm: Use a singular subject for grammatical cleanliness

	  a GTT DRM MM object, which provides an address space pool for

	  object allocation.  In a KMS configuration, the driver

	  needs to allocate and initialize a command ring buffer following

	  core GEM initialization.  Most UMA devices have a so-called

	  core GEM initialization.  A UMA device usually has a so-called

	  "stolen" memory region, which provides space for the initial

	  framebuffer and large, contiguous memory regions required by the

	  device.  This space is not typically managed by GEM, and must

      a client calls the vblank wait ioctl above.

    </para>

    <para>

      Devices that don't provide a count register may simply use an

      A device that doesn't provide a count register may simply use an

      internal atomic counter incremented on every vertical blank

      interrupt, and can make their enable and disable vblank

      functions into no-ops.

      interrupt (and then treat the enable_vblank() and disable_vblank()

      callbacks as no-ops).

    </para>

  </sect1>