| .. SPDX-License-Identifier: GPL-2.0 |
| |
| 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 |
