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>
diff --git a/Documentation/video4linux/cx2341x/fw-encoder-api.txt b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
index f74b0ae..001c686 100644
--- a/Documentation/video4linux/cx2341x/fw-encoder-api.txt
+++ b/Documentation/video4linux/cx2341x/fw-encoder-api.txt
@@ -270,11 +270,17 @@
 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.
 
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