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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/i2c/busses/i2c-voodoo3
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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1Kernel driver i2c-voodoo3
2
3Supported adapters:
4 * 3dfx Voodoo3 based cards
5 * Voodoo Banshee based cards
6
7Authors:
8 Frodo Looijaard <frodol@dds.nl>,
9 Philip Edelbrock <phil@netroedge.com>,
10 Ralph Metzler <rjkm@thp.uni-koeln.de>,
11 Mark D. Studebaker <mdsxyz123@yahoo.com>
12
13Main contact: Philip Edelbrock <phil@netroedge.com>
14
15The code is based upon Ralph's test code (he did the hard stuff ;')
16
17Description
18-----------
19
20The 3dfx Voodoo3 chip contains two I2C interfaces (aka a I2C 'master' or
21'host').
22
23The first interface is used for DDC (Data Display Channel) which is a
24serial channel through the VGA monitor connector to a DDC-compliant
25monitor. This interface is defined by the Video Electronics Standards
26Association (VESA). The standards are available for purchase at
27http://www.vesa.org .
28
29The second interface is a general-purpose I2C bus. The intent by 3dfx was
30to allow manufacturers to add extra chips to the video card such as a
31TV-out chip such as the BT869 or possibly even I2C based temperature
32sensors like the ADM1021 or LM75.
33
34Stability
35---------
36
37Seems to be stable on the test machine, but needs more testing on other
38machines. Simultaneous accesses of the DDC and I2C busses may cause errors.
39
40Supported Devices
41-----------------
42
43Specifically, this driver was written and tested on the '3dfx Voodoo3 AGP
443000' which has a tv-out feature (s-video or composite). According to the
45docs and discussions, this code should work for any Voodoo3 based cards as
46well as Voodoo Banshee based cards. The DDC interface has been tested on a
47Voodoo Banshee card.
48
49Issues
50------
51
52Probably many, but it seems to work OK on my system. :')
53
54
55External Device Connection
56--------------------------
57
58The digital video input jumpers give availability to the I2C bus.
59Specifically, pins 13 and 25 (bottom row middle, and bottom right-end) are
60the I2C clock and I2C data lines, respectively. +5V and GND are probably
61also easily available making the addition of extra I2C/SMBus devices easy
62to implement.