| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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. |