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Mark D. Studebaker
11bf8e8f81
git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@1714 7894878c-1315-0410-8ee3-d5d059ff63e0
84 lines
2.7 KiB
Plaintext
84 lines
2.7 KiB
Plaintext
Kernel driver `i2c-voodoo3.o'
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Status: 'Beta' and still under development and testing
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Supported adapters:
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* 3dfx Voodoo3 based cards
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* Voodoo Banshee based cards
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Author: Frodo Looijaard <frodol@dds.nl>, Philip Edelbrock
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<phil@netroedge.com>, Ralph Metzler <rjkm@thp.uni-koeln.de>,
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and Mark D. Studebaker <mdsxyz123@yahoo.com>
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Main contact: Philip Edelbrock <phil@netroedge.com>
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The code is based upon Ralph's test code (he did the hard stuff ;')
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Module Parameters
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-----------------
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(none)
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Description
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-----------
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The 3dfx Voodoo3 chip contains two I2C interfaces (aka a I2C 'master'
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or 'host').
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The first interface is used for DDC (Data Display Channel)
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which is a serial channel through the VGA monitor connector
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to a DDC-compliant monitor. This interface is defined by the
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Video Electronics Standards Association (VESA). The standards
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are available for purchase at http://www.vesa.org .
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The second interface is a general-purpose I2C bus.
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The intent by 3dfx was to allow manufacturers to add extra
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chips to the video card such as a TV-out chip such as the BT869 or possibly
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even I2C based temperature sensors like the ADM1021 or LM75.
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The 'feature' set of this driver is based on the i2c-piix4 (SMBus)
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features. I.e., SMBus byte reads and writes, as well as detected faults in
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transmission. Quick reads/writes, block transactions, word transactions,
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are yet unwritten but are probably not too hard to add.
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This driver uses the i2c-algo-bit module which must be
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modprobed and/or enabled in your kernel
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(Character Devices -> I2C Support -> I2C Bit-Banging Interfaces).
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Stability
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---------
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Seems to be stable on the test machine, but needs more testing on other
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machines.
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Simultaneous accesses of the DDC and I2C busses may cause errors.
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Supported Devices
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-----------------
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Specifically, this driver was written and tested on the '3dfx Voodoo3 AGP
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3000' which has a tv-out feature (s-video or composite). According to the
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docs and discussions, this code should work for any Voodoo3 based cards as
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well as Voodoo Banshee based cards. The DDC interface has been tested
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on a Voodoo Banshee card.
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Features
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--------
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This driver controls the I2C controller of the Voodoo3 chip. 'byte read'
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transactions and 'data_byte write' transactions are supported, but all else
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is not (but is probably easy to add if the need arises).
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Issues
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------
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Probably many, but it seems to work OK on my system. :')
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External Device Connection
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--------------------------
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The digital video input jumpers give availability to the I2C bus.
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Specifically, pins 13 and 25 (bottom row middle, and bottom right-end) are
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the I2C clock and I2C data lines, respectively. +5V and GND are probably
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also easily available making the addition of extra I2C/SMBus devices easy
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to implement.
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