On Sat, 9 Nov 2002 [EMAIL PROTECTED] wrote:
> Does DDC require OS support, such as loaded I2C drivers?
There are two versions: DDC1 and DDC2. These are not the same as the EDID
version reported in the DDC info, and DDC2 is split into at least three).
Some monitors support DDC1 but not DDC2 and vice-versa.
For our mga driver there are actually three DDC implementations: DDC1,
DDC2 and DDCvbe. Each can be turned off separately in the "Monitor"
Section of the config file, with one of:
Option "noDDC1"
Option "noDDC2"
Option "noDDCvbe"
DDCvbe uses the video BIOS to return the DDC info.
DDC2 requires the XFree86 I2C module, but not I think kernel I2C support.
It does use a micro-second delay function; if you don't provide
anything better it can revert to an uncalibrated loop which
is probably far too fast current hardware.
As far as I know the DDC1 code requires no specific operating system
support, but it doesn't support DDC2 only monitors, and may fail
if called after the DDC2 support (the monitor can get stuck in
DDC2 mode).
--
Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge
[EMAIL PROTECTED] http://www.dpmms.cam.ac.uk/~werdna
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