This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / Documentation / i2c / busses / i2c-voodoo3

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+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.