[CentOS] Completely lost X (was system-config-display wronglysets up Viewsonic VG730m monitor)

Fri Feb 29 09:04:54 UTC 2008
Anne Wilson <cannewilson at googlemail.com>

On Thursday 28 February 2008 22:24:08 John R Pierce wrote:
> Anne Wilson wrote:
> >> I was reluctant to state this because I have no authoritative knowledge
> >> on these things but if you change video cables, I think that you need to
> >> reboot to get the video chipset to properly recognize the cable/monitor
> >> connected.
> >
> > I'm pretty sure you do.  I had done that, though.
>
> on VGA, yes, the video controller can only read the "VESA ID" extended
> format information when its reset, its a horrible mess of a kludge
> interface as IBM had only alloted like 3 pins for a 1-of-8 model monitor
> specification back in 1984 or whenever the first VGA was designed.
> VESA created this very complex dance where the V sync line is used to
> clock serial data over those pins, and its only read when the monitor
> sync is stopped for some length of time, then started, the video
> controllers capture this data and save it so the host can later read
> it.    I forget all the specifics, I had to work with this stuff in the
> mid 1990s when it was devised.
>
> I /think/ on DVI its a lot better, but I've not actually worked with
> that at a low level so I can't confirm this from direct experience.
>
My problem was that the monitor blinked, when on DVI.  One possible 
explanation is that the lead is fitting poorly.  I don't know the technical 
details, but you know how these leads have a barrel-shaped thingy that I 
think is a power-smoother or some such?  That is pretty close to the 
rectangular lead, bot possibly not close enough.  I got the feeling that 
the 'stylish' design of the monitor stand may be pushing it slightly.  I 
don't know whether I can get a lead where it is either shorter or longer at 
that point.

The other possibility that has been suggested is that the DVI interface on the 
monitor may be poorly supported on the current kernel.  If that's so, it may 
be cured on later ones.

Both are possibilities that I can test, though not immediately.

Anne
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