Merge branch 'topic/asoc' into for-linus

[pandora-kernel.git] / Documentation / sound / alsa / OSS-Emulation.txt

diff --git a/Documentation/sound/alsa/OSS-Emulation.txt b/Documentation/sound/alsa/OSS-Emulation.txt
index ec2a025..022aaeb 100644 (file)
--- a/Documentation/sound/alsa/OSS-Emulation.txt
+++ b/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
 ====================
 
@@ -288,10 +303,3 @@ ICE1712 supports only the unconventional format, interleaved
 the buffer as the conventional (mono or 2-channels, 8 or 16bit) format
 on OSS.
 
-USB devices
------------
-Some USB devices support only 24bit format packed in 3bytes.  This
-format is not supported by OSS and no conversion is provided by kernel
-OSS emulation.  You can use the user-space OSS emulation via libaoss
-instead.
-