V4L/DVB (4987): Improve cx2341x documentation

Document the program index table format, removed unused interrupt documentation
and improve the documentation regarding the audio mode (stereo/joint/dual/mono).

Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/video4linux/cx2341x/fw-decoder-api.txt

···
 	Setup firmware to notify the host about a particular event.
 	Counterpart to API 0xD5
 Param[0]
-	Event: 0=Audio mode change between stereo and dual channel
+	Event: 0=Audio mode change between mono, (joint) stereo and dual channel.
 	Event: 3=Decoder started
 	Event: 4=Unknown: goes off 10-15 times per second while decoding.
 	Event: 5=Some sync event: goes off once per frame.

Documentation/video4linux/cx2341x/fw-encoder-api.txt

···
 		'01'=JointStereo
 		'10'=Dual
 		'11'=Mono
-		Note: testing seems to indicate that Mono and possibly
-		JointStereo are not working (default to stereo).
-		Dual does work, though.
+		Note: the cx23415 cannot decode Joint Stereo properly.
 
 	  10:11 Mode Extension used in joint_stereo mode.
 		In Layer I and II they indicate which subbands are in
···
 Enum 	199/0xC7
 Description
 	Sets the Program Index Information.
+	The information is stored as follows:
+
+	struct info {
+		u32 length;		// Length of this frame
+		u32 offset_low;		// Offset in the file of the
+		u32 offset_high;	// start of this frame
+		u32 mask1;		// Bits 0-1 are the type mask:
+					// 1=I, 2=P, 4=B
+		u32 pts;		// The PTS of the frame
+		u32 mask2;		// Bit 0 is bit 32 of the pts.
+	};
+	u32 table_ptr;
+	struct info index[400];
+
+	The table_ptr is the encoder memory address in the table were
+	*new* entries will be written. Note that this is a ringbuffer,
+	so the table_ptr will wraparound.
 Param[0]
 	Picture Mask:
 	    0=No index capture
 	    1=I frames
 	    3=I,P frames
 	    7=I,P,B frames
+	(Seems to be ignored, it always indexes I, P and B frames)
 Param[1]
 	Elements requested (up to 400)
 Result[0]
-	Offset in SDF memory of the table.
+	Offset in the encoder memory of the start of the table.
 Result[1]
 	Number of allocated elements up to a maximum of Param[1]
 

Documentation/video4linux/cx2341x/fw-memory.txt

···
 29 Encoder VBI capture
 28 Encoder Video Input Module reset event
 27 Encoder DMA complete
-26
-25 Decoder copy protect detection event
 24 Decoder audio mode change detection event (through event notification)
-23
 22 Decoder data request
-21 Decoder I-Frame? done
 20 Decoder DMA complete
 19 Decoder VBI re-insertion
 18 Decoder DMA err (linked-list bad)