diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /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!
Diffstat (limited to 'Documentation/i2c/busses/i2c-voodoo3')
-rw-r--r-- | Documentation/i2c/busses/i2c-voodoo3 | 62 |
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diff --git a/Documentation/i2c/busses/i2c-voodoo3 b/Documentation/i2c/busses/i2c-voodoo3 new file mode 100644 index 000000000000..62d90a454d39 --- /dev/null +++ b/Documentation/i2c/busses/i2c-voodoo3 | |||
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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. | ||