4 files changed, 36 insertions, 8 deletions
diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index a20a45b45c30..58af32b01b90 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -128,16 +128,44 @@ X!Edrivers/base/interface.c
 !Edrivers/base/platform.c
 !Edrivers/base/bus.c
      </sect1>
-     <sect1><title>Device Drivers DMA Management</title>
+     <sect1>
+       <title>Buffer Sharing and Synchronization</title>
+       <para>
+         The dma-buf subsystem provides the framework for sharing buffers
+         for hardware (DMA) access across multiple device drivers and
+         subsystems, and for synchronizing asynchronous hardware access.
+       </para>
+       <para>
+         This is used, for example, by drm "prime" multi-GPU support, but
+         is of course not limited to GPU use cases.
+       </para>
+       <para>
+         The three main components of this are: (1) dma-buf, representing
+         a sg_table and exposed to userspace as a file descriptor to allow
+         passing between devices, (2) fence, which provides a mechanism
+         to signal when one device as finished access, and (3) reservation,
+         which manages the shared or exclusive fence(s) associated with
+         the buffer.
+       </para>
+       <sect2><title>dma-buf</title>
 !Edrivers/dma-buf/dma-buf.c
+!Iinclude/linux/dma-buf.h
+       </sect2>
+       <sect2><title>reservation</title>
+!Pdrivers/dma-buf/reservation.c Reservation Object Overview
+!Edrivers/dma-buf/reservation.c
+!Iinclude/linux/reservation.h
+       </sect2>
+       <sect2><title>fence</title>
 !Edrivers/dma-buf/fence.c
-!Edrivers/dma-buf/seqno-fence.c
 !Iinclude/linux/fence.h
+!Edrivers/dma-buf/seqno-fence.c
 !Iinclude/linux/seqno-fence.h
-!Edrivers/dma-buf/reservation.c
-!Iinclude/linux/reservation.h
 !Edrivers/dma-buf/sync_file.c
 !Iinclude/linux/sync_file.h
+       </sect2>
+     </sect1>
+     <sect1><title>Device Drivers DMA Management</title>
 !Edrivers/base/dma-coherent.c
 !Edrivers/base/dma-mapping.c
      </sect1>
diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
index e09025db92bd..21a3dde8f95d 100644
--- a/Documentation/DocBook/media/v4l/io.xml
+++ b/Documentation/DocBook/media/v4l/io.xml
@@ -88,7 +88,7 @@ function.<footnote>
 <structfield>capabilities</structfield> field of &v4l2-capability;
 returned by the &VIDIOC-QUERYCAP; ioctl is set. There are two
 streaming methods, to determine if the memory mapping flavor is
-supported applications must call the &VIDIOC-REQBUFS; ioctl.</para>
+supported applications must call the &VIDIOC-REQBUFS; ioctl with the memory type set to <constant>V4L2_MEMORY_MMAP</constant>.</para>
 
     <para>Streaming is an I/O method where only pointers to buffers
 are exchanged between application and driver, the data itself is not
@@ -369,7 +369,7 @@ rest should be evident.</para>
 <structfield>capabilities</structfield> field of &v4l2-capability;
 returned by the &VIDIOC-QUERYCAP; ioctl is set. If the particular user
 pointer method (not only memory mapping) is supported must be
-determined by calling the &VIDIOC-REQBUFS; ioctl.</para>
+determined by calling the &VIDIOC-REQBUFS; ioctl with the memory type set to <constant>V4L2_MEMORY_USERPTR</constant>.</para>
 
     <para>This I/O method combines advantages of the read/write and
 memory mapping methods. Buffers (planes) are allocated by the application
diff --git a/Documentation/DocBook/media/v4l/pixfmt-z16.xml b/Documentation/DocBook/media/v4l/pixfmt-z16.xml
index 3d87e4bf87b8..1d9cb1684bd3 100644
--- a/Documentation/DocBook/media/v4l/pixfmt-z16.xml
+++ b/Documentation/DocBook/media/v4l/pixfmt-z16.xml
@@ -5,7 +5,7 @@
   </refmeta>
   <refnamediv>
     <refname><constant>V4L2_PIX_FMT_Z16</constant></refname>
-    <refpurpose>Interleaved grey-scale image, e.g. from a stereo-pair</refpurpose>
+    <refpurpose>16-bit depth data with distance values at each pixel</refpurpose>
   </refnamediv>
   <refsect1>
     <title>Description</title>
diff --git a/Documentation/DocBook/media/v4l/vidioc-reqbufs.xml b/Documentation/DocBook/media/v4l/vidioc-reqbufs.xml
index 0f193fda0470..6f529e100ea4 100644
--- a/Documentation/DocBook/media/v4l/vidioc-reqbufs.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-reqbufs.xml
@@ -6,7 +6,7 @@
 
   <refnamediv>
     <refname>VIDIOC_REQBUFS</refname>
-    <refpurpose>Initiate Memory Mapping or User Pointer I/O</refpurpose>
+    <refpurpose>Initiate Memory Mapping, User Pointer or DMA Buffer I/O</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>