monitor detection through ddc/edid stuff.

[Sven Luther <sven.luther@wanadoo.fr>]

Hello,

I am currently working on a 3dlabs wildcat vp fbdev driver (my 560 died, but i
got a 880 Pro :). And i have some questions with the monitor detection and
ddc/edid stuff.

I have looked over fbmon.c, and foung that it contains code for parsing the
EDID data, but not for actually reading it, apart the get_EDID_from_firmware
which is rather primitive, and doesn't actually do anything (i suppose that
the edid_info.dummy is read from the x86 bios in some other function).

I also have quickly overviewed the radeon driver, which has a function to read
the EDID either from the BIOS or the pmac OF. There seem to be no code
whatsoever that adds proper EDID reading through the graphic card directly,
like it is done in XFree86, where one can do in the individual drivers (using
i2c stuff also) :

	...
	pBus->BusName = "DDC";
	pBus->I2CUDelay = WildcatVPI2CUDelay;
	pBus->I2CPutBits = WildcatVPI2CPutBits;
	pBus->I2CGetBits = WildcatVPI2CGetBits;

These three being smallish functions to delay a bit, and to put/get bits in
the DCC Clock/Data Out/In registers.

And then :

	pMon = xf86DoEDID_DDC2(pScrn->scrnIndex, pBus);

There is also a DCC1 function i think, or something such.

Would it make sense to implement such a feature in fbmon.c ? Is fbmon.c the
right place for this ? Is this already implemented somewhere else, or maybe in
some private tree somewhere ? 

As i understand this, we would need some place to set the those three
function, and then a common function to actually do a real EDID reading
through the graphic card (get_EDID_from_harware ?).

Does this make sense ? Any hint on how to best implement this ? 

Friendly,

Sven Luther




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