Help from Gurus on modes and timing and frame buffers needed!

Kevin B. Hendricks khendricks at
Sat Nov 10 05:47:34 EST 2001


> 	When you do get all this figured out, could you please post a summary.
> I think there's quite a few people who would love to be able to
> interpret this stuff :-)

I think I am now there.  It seems that the interpret_edid.c code that
comes with XFree86 4.1.0 in the xc/programs/Xserver/hw/xfree86/ddc/ is
incorrectly interpreting the sync flags.  They are shifting right one bit
too many (why "and" a byte value with 0x18 and then >> 4 ... it makes no
sense - they should have just done >> 3).

The EDID SYNC_T of 3 means SYNC_SEPARATE.  Once that is the case, you can
use other bits in the word (part of MISC which is also over shifted right)
to determine the flags of +/- HSYNC, VSYNC.

So with fixes to that code, EDID data can easily tell you all you need to
know to make your own mode lines.

I will try and summarize it all up in a readme of some sort and send it to
the mailing list.

Thanks for eveyone's help.


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