1 .. SPDX-License-Identifier: GPL-2.0
2
3 The bttv driver
4 ===============
5
6 bttv and sound mini howto
7 -------------------------
8
9 There are a lot of different bt848/849/878/879
10 Making video work often is not a big deal, bec
11 completely by the bt8xx chip, which is common
12 sound is handled in slightly different ways on
13
14 To handle the grabber boards correctly, there
15 bttv-cards.c, which holds the information requ
16 Sound will work only, if the correct entry is
17 makes no difference). The bttv driver prints
18 log, telling which card type is used. Like th
19
20 bttv0: model: BT848(Hauppauge old) [au
21
22 You should verify this is correct. If it isn'
23 correct board type as insmod argument, ``insmo
24 example. The file Documentation/admin-guide/m
25 of valid arguments for card.
26
27 If your card isn't listed there, you might che
28 new entries which are not listed yet. If ther
29 card, you can check if one of the existing ent
30 (just trial and error...).
31
32 Some boards have an extra processor for sound
33 and other nice features. The msp34xx chips ar
34 example. If your board has one, you might hav
35 module like ``msp3400`` to make sound work. I
36 chip used on your board: Bad luck. Start wri
37 you might want to check the video4linux mailin
38
39 Of course you need a correctly installed sound
40 speakers connected directly to the grabber boa
41 mixer settings too. ALSA for example has ever
42
43
44 How sound works in detail
45 ~~~~~~~~~~~~~~~~~~~~~~~~~
46
47 Still doesn't work? Looks like some driver ha
48 Below is a do-it-yourself description for you.
49
50 The bt8xx chips have 32 general purpose pins,
51 these pins. One register is the output enable
52 (``BT848_GPIO_OUT_EN``), it says which pins ar
53 bt848 chip. Another one is the data register
54 you can get/set the status if these pins. The
55 and output.
56
57 Most grabber board vendors use these pins to c
58 which does the sound routing. But every board
59 These pins are also used by some companies to
60 receiver chips. Some boards use the i2c bus i
61 to connect the mux chip.
62
63 As mentioned above, there is a array which hol
64 information for each known board. You basical
65 line for your board. The important fields are
66
67 struct tvcard
68 {
69 [ ... ]
70 u32 gpiomask;
71 u32 audiomux[6]; /* Tuner, Radio, exte
72 };
73
74 gpiomask specifies which pins are used to cont
75 The corresponding bits in the output enable re
76 (``BT848_GPIO_OUT_EN``) will be set as these p
77 bt848 chip.
78
79 The ``audiomux[]`` array holds the data values
80 (i.e. which pins must be high/low for tuner/mu
81 written to the data register (``BT848_GPIO_DAT
82 mux.
83
84
85 What you have to do is figure out the correct
86 the audiomux array. If you have Windows and t
87 card installed, you might to check out if you
88 values used by the windows driver. A tool to
89 from http://btwincap.sourceforge.net/download.
90
91 You might also dig around in the ``*.ini`` fil
92 You can have a look at the board to see which
93 connected at all and then start trial-and-erro
94
95
96 Starting with release 0.7.41 bttv has a number
97 make the gpio debugging easier:
98
99 ================= ==============
100 bttv_gpio=0/1 enable/disable
101 gpiomask=n set the gpioma
102 audiomux=i,j,... set the values
103 audioall=a set the values
104 value for all
105 out which effe
106 ================= ==============
107
108 The messages printed with ``bttv_gpio=1`` look
109
110 bttv0: gpio: en=00000027, out=00000024
111
112 en = output _en_able register (BT84
113 out = _out_put bits of the data regi
114 i.e. BT848_GPIO_DATA & BT848_G
115 in = _in_put bits of the data regis
116 i.e. BT848_GPIO_DATA & ~BT848_
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