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Diffstat (limited to 'Documentation/media/v4l-drivers/cx88.rst')
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diff --git a/Documentation/media/v4l-drivers/cx88.rst b/Documentation/media/v4l-drivers/cx88.rst new file mode 100644 index 000000000000..d8f3a014726a --- /dev/null +++ b/Documentation/media/v4l-drivers/cx88.rst @@ -0,0 +1,163 @@ +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 |