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+The cx88 driver
+===============
+
+Author: Gerd Hoffmann
+
+This is a v4l2 device driver for the cx2388x chip.
+
+
+Current status
+--------------
+
+video
+ - Works.
+ - Overlay isn't supported.
+
+audio
+ - Works. The TV standard detection is made by the driver, as the
+ hardware has bugs to auto-detect.
+ - audio data dma (i.e. recording without loopback cable to the
+ sound card) is supported via cx88-alsa.
+
+vbi
+ - Works.
+
+
+How to add support for new cards
+--------------------------------
+
+The driver needs some config info for the TV cards. This stuff is in
+cx88-cards.c. If the driver doesn't work well you likely need a new
+entry for your card in that file. Check the kernel log (using dmesg)
+to see whenever the driver knows your card or not. There is a line
+like this one:
+
+.. code-block:: none
+
+ cx8800[0]: subsystem: 0070:3400, board: Hauppauge WinTV \
+ 34xxx models [card=1,autodetected]
+
+If your card is listed as "board: UNKNOWN/GENERIC" it is unknown to
+the driver. What to do then?
+
+1) Try upgrading to the latest snapshot, maybe it has been added
+ meanwhile.
+2) You can try to create a new entry yourself, have a look at
+ cx88-cards.c. If that worked, mail me your changes as unified
+ diff ("diff -u").
+3) Or you can mail me the config information. We need at least the
+ following information to add the card:
+
+ - the PCI Subsystem ID ("0070:3400" from the line above,
+ "lspci -v" output is fine too).
+ - the tuner type used by the card. You can try to find one by
+ trial-and-error using the tuner=<n> insmod option. If you
+ know which one the card has you can also have a look at the
+ list in CARDLIST.tuner
+
+Documentation missing at the cx88 datasheet
+-------------------------------------------
+
+MO_OUTPUT_FORMAT (0x310164)
+
+.. code-block:: none
+
+ Previous default from DScaler: 0x1c1f0008
+ Digit 8: 31-28
+ 28: PREVREMOD = 1
+
+ Digit 7: 27-24 (0xc = 12 = b1100 )
+ 27: COMBALT = 1
+ 26: PAL_INV_PHASE
+ (DScaler apparently set this to 1, resulted in sucky picture)
+
+ Digits 6,5: 23-16
+ 25-16: COMB_RANGE = 0x1f [default] (9 bits -> max 512)
+
+ Digit 4: 15-12
+ 15: DISIFX = 0
+ 14: INVCBF = 0
+ 13: DISADAPT = 0
+ 12: NARROWADAPT = 0
+
+ Digit 3: 11-8
+ 11: FORCE2H
+ 10: FORCEREMD
+ 9: NCHROMAEN
+ 8: NREMODEN
+
+ Digit 2: 7-4
+ 7-6: YCORE
+ 5-4: CCORE
+
+ Digit 1: 3-0
+ 3: RANGE = 1
+ 2: HACTEXT
+ 1: HSFMT
+
+0x47 is the sync byte for MPEG-2 transport stream packets.
+Datasheet incorrectly states to use 47 decimal. 188 is the length.
+All DVB compliant frontends output packets with this start code.
+
+Hauppauge WinTV cx88 IR information
+-----------------------------------
+
+The controls for the mux are GPIO [0,1] for source, and GPIO 2 for muting.
+
+====== ======== =================================================
+GPIO0 GPIO1
+====== ======== =================================================
+ 0 0 TV Audio
+ 1 0 FM radio
+ 0 1 Line-In
+ 1 1 Mono tuner bypass or CD passthru (tuner specific)
+====== ======== =================================================
+
+GPIO 16(I believe) is tied to the IR port (if present).
+
+
+From the data sheet:
+
+- Register 24'h20004 PCI Interrupt Status
+
+ - bit [18] IR_SMP_INT Set when 32 input samples have been collected over
+ - gpio[16] pin into GP_SAMPLE register.
+
+What's missing from the data sheet:
+
+- Setup 4KHz sampling rate (roughly 2x oversampled; good enough for our RC5
+ compat remote)
+- set register 0x35C050 to 0xa80a80
+- enable sampling
+- set register 0x35C054 to 0x5
+- enable the IRQ bit 18 in the interrupt mask register (and
+ provide for a handler)
+
+GP_SAMPLE register is at 0x35C058
+
+Bits are then right shifted into the GP_SAMPLE register at the specified
+rate; you get an interrupt when a full DWORD is received.
+You need to recover the actual RC5 bits out of the (oversampled) IR sensor
+bits. (Hint: look for the 0/1and 1/0 crossings of the RC5 bi-phase data) An
+actual raw RC5 code will span 2-3 DWORDS, depending on the actual alignment.
+
+I'm pretty sure when no IR signal is present the receiver is always in a
+marking state(1); but stray light, etc can cause intermittent noise values
+as well. Remember, this is a free running sample of the IR receiver state
+over time, so don't assume any sample starts at any particular place.
+
+Additional info
+~~~~~~~~~~~~~~~
+
+This data sheet (google search) seems to have a lovely description of the
+RC5 basics:
+http://www.atmel.com/dyn/resources/prod_documents/doc2817.pdf
+
+This document has more data:
+http://www.nenya.be/beor/electronics/rc5.htm
+
+This document has a how to decode a bi-phase data stream:
+http://www.ee.washington.edu/circuit_archive/text/ir_decode.txt
+
+This document has still more info:
+http://www.xs4all.nl/~sbp/knowledge/ir/rc5.htm