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Diffstat (limited to 'Documentation/i2c/busses/i2c-voodoo3')
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diff --git a/Documentation/i2c/busses/i2c-voodoo3 b/Documentation/i2c/busses/i2c-voodoo3 new file mode 100644 index 00000000000..62d90a454d3 --- /dev/null +++ b/Documentation/i2c/busses/i2c-voodoo3 @@ -0,0 +1,62 @@ +Kernel driver i2c-voodoo3 + +Supported adapters: + * 3dfx Voodoo3 based cards + * Voodoo Banshee based cards + +Authors: + Frodo Looijaard <frodol@dds.nl>, + Philip Edelbrock <phil@netroedge.com>, + Ralph Metzler <rjkm@thp.uni-koeln.de>, + Mark D. Studebaker <mdsxyz123@yahoo.com> + +Main contact: Philip Edelbrock <phil@netroedge.com> + +The code is based upon Ralph's test code (he did the hard stuff ;') + +Description +----------- + +The 3dfx Voodoo3 chip contains two I2C interfaces (aka a I2C 'master' or +'host'). + +The first interface is used for DDC (Data Display Channel) which is a +serial channel through the VGA monitor connector to a DDC-compliant +monitor. This interface is defined by the Video Electronics Standards +Association (VESA). The standards are available for purchase at +http://www.vesa.org . + +The second interface is a general-purpose I2C bus. The intent by 3dfx was +to allow manufacturers to add extra chips to the video card such as a +TV-out chip such as the BT869 or possibly even I2C based temperature +sensors like the ADM1021 or LM75. + +Stability +--------- + +Seems to be stable on the test machine, but needs more testing on other +machines. Simultaneous accesses of the DDC and I2C busses may cause errors. + +Supported Devices +----------------- + +Specifically, this driver was written and tested on the '3dfx Voodoo3 AGP +3000' which has a tv-out feature (s-video or composite). According to the +docs and discussions, this code should work for any Voodoo3 based cards as +well as Voodoo Banshee based cards. The DDC interface has been tested on a +Voodoo Banshee card. + +Issues +------ + +Probably many, but it seems to work OK on my system. :') + + +External Device Connection +-------------------------- + +The digital video input jumpers give availability to the I2C bus. +Specifically, pins 13 and 25 (bottom row middle, and bottom right-end) are +the I2C clock and I2C data lines, respectively. +5V and GND are probably +also easily available making the addition of extra I2C/SMBus devices easy +to implement. |