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Commit | Line | Data |
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1da177e4 LT |
1 | Kernel driver i2c-voodoo3 |
2 | ||
3 | Supported adapters: | |
4 | * 3dfx Voodoo3 based cards | |
5 | * Voodoo Banshee based cards | |
6 | ||
7 | Authors: | |
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 | ||
13 | Main contact: Philip Edelbrock <phil@netroedge.com> | |
14 | ||
15 | The code is based upon Ralph's test code (he did the hard stuff ;') | |
16 | ||
17 | Description | |
18 | ----------- | |
19 | ||
20 | The 3dfx Voodoo3 chip contains two I2C interfaces (aka a I2C 'master' or | |
21 | 'host'). | |
22 | ||
23 | The first interface is used for DDC (Data Display Channel) which is a | |
24 | serial channel through the VGA monitor connector to a DDC-compliant | |
25 | monitor. This interface is defined by the Video Electronics Standards | |
26 | Association (VESA). The standards are available for purchase at | |
27 | http://www.vesa.org . | |
28 | ||
29 | The second interface is a general-purpose I2C bus. The intent by 3dfx was | |
30 | to allow manufacturers to add extra chips to the video card such as a | |
31 | TV-out chip such as the BT869 or possibly even I2C based temperature | |
32 | sensors like the ADM1021 or LM75. | |
33 | ||
34 | Stability | |
35 | --------- | |
36 | ||
37 | Seems to be stable on the test machine, but needs more testing on other | |
38 | machines. Simultaneous accesses of the DDC and I2C busses may cause errors. | |
39 | ||
40 | Supported Devices | |
41 | ----------------- | |
42 | ||
43 | Specifically, this driver was written and tested on the '3dfx Voodoo3 AGP | |
44 | 3000' which has a tv-out feature (s-video or composite). According to the | |
45 | docs and discussions, this code should work for any Voodoo3 based cards as | |
46 | well as Voodoo Banshee based cards. The DDC interface has been tested on a | |
47 | Voodoo Banshee card. | |
48 | ||
49 | Issues | |
50 | ------ | |
51 | ||
52 | Probably many, but it seems to work OK on my system. :') | |
53 | ||
54 | ||
55 | External Device Connection | |
56 | -------------------------- | |
57 | ||
58 | The digital video input jumpers give availability to the I2C bus. | |
59 | Specifically, pins 13 and 25 (bottom row middle, and bottom right-end) are | |
60 | the I2C clock and I2C data lines, respectively. +5V and GND are probably | |
61 | also easily available making the addition of extra I2C/SMBus devices easy | |
62 | to implement. |