diff --git a/[refs] b/[refs]
index e856cdd8dd86..712a355230c6 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3b194401a31b8df9a07a1850e3fe44fc7ba832a4
+refs/heads/master: 1919de0a9e939ef4f9453ef1630ca1345991e144
diff --git a/trunk/Documentation/sound/alsa/OSS-Emulation.txt b/trunk/Documentation/sound/alsa/OSS-Emulation.txt
index ec2a02541d5b..bfa0c9aacb4b 100644
--- a/trunk/Documentation/sound/alsa/OSS-Emulation.txt
+++ b/trunk/Documentation/sound/alsa/OSS-Emulation.txt
@@ -278,6 +278,21 @@ current mixer configuration by reading and writing the whole file
 image.
 
 
+Duplex Streams
+==============
+
+Note that when attempting to use a single device file for playback and
+capture, the OSS API provides no way to set the format, sample rate or
+number of channels different in each direction.  Thus
+	io_handle = open("device", O_RDWR)
+will only function correctly if the values are the same in each direction.
+
+To use different values in the two directions, use both
+	input_handle = open("device", O_RDONLY)
+	output_handle = open("device", O_WRONLY)
+and set the values for the corresponding handle.
+
+
 Unsupported Features
 ====================