V4L/DVB (4202): allow selecting CX2341x port mode

CX2341X port was always set to 'memory', but 'streaming' is also possible

ivtv uses the memory (DMA) interface with the CX2341X, while pvrusb2 and
cx88-blackbird use the streaming interface. This setting is now selectable
by the driver.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/Documentation/video4linux/cx2341x/fw-encoder-api.txt b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
index f74b0ae4a769..001c68644b08 100644
--- a/Documentation/video4linux/cx2341x/fw-encoder-api.txt
+++ b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
@@ -270,11 +270,17 @@ Param[0]
 Name    CX2341X_ENC_SET_OUTPUT_PORT
 Enum    187/0xBB
 Description
-        Assign stream output port (not recommended you change setting from default)
+        Assign stream output port. Normally 0 when the data is copied through
+        the PCI bus (DMA), and 1 when the data is streamed to another chip
+        (pvrusb and cx88-blackbird).
 Param[0]
         0=Memory (default)
         1=Streaming
         2=Serial
+Param[1]
+        Unknown, but leaving this to 0 seems to work best. Indications are that
+        this might have to do with USB support, although passing anything but 0
+        onl breaks things.
 
 -------------------------------------------------------------------------------