path: root/Documentation/i2c/busses/i2c-voodoo3
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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/i2c/busses/i2c-voodoo3
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!
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+Kernel driver i2c-voodoo3
+Supported adapters:
+ * 3dfx Voodoo3 based cards
+ * Voodoo Banshee based cards
+ 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 ;')
+The 3dfx Voodoo3 chip contains two I2C interfaces (aka a I2C 'master' or
+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.
+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.
+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.