[Openchrome-devel] [Bug 91966] No signal to monitor with X and openchrome using VX855 chipset graphics

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=91966

--- Comment #257 from Kevin Brace <kevinbrace at gmx.com> ---
(In reply to Justin Chevrier from comment #252)

Hi Justin,

> (In reply to Kevin Brace from comment #247)
> 
> DVI via DVI-I only works if I apply my patch ( attachment 121922 [details]
> [review] ) that adds a "VIA_DEVICE_LCD" to the big table. If I apply the
> patch DVI on DVI-I works, but VGA does not.

I will have more time to spend on Thursday and Friday on analyzing what is
going on, but that being said, it appears that without "VIA_DEVICE_LCD" option
specified in the known device ID table, DVI / LVDS interface does not work.
Over the past few days, I was experimenting with removing the notorious device
ID table completely, and obviously, I was encountering hidden problem and bug
of the device driver that was overlooked by the previous developers.
After analyzing the code, it is my view that this table is primarily used for
remembering which known device supports DVI / LVDS interface, and other than
that, it really does not have any useful purpose anymore.
One of the reason I have made some progress in fixing this DVI related bug is
due to myself obtaining a netbook with a DVI connector coming out of the
laptop.
This DVI is from the integrated TMDS inside VX700 chipset.
It appears that its functionality, in terms of register mapping, is equivalent
to the one that comes with VX900 chipset.
For now, DVI works since the netbook laptop I used is registered with the known
device table.
Of course, if I remove the known device table, flat panel connected to the LVDS
interface does not work.
That being said, monitors connected to VGA interface (via DVI to VGA adapter)
and DVI do get automatically detected, and works fine.
I am trying to figure out right now how to make the DVI / LVDS interface
detection code work without this table, and it might take maybe a few days to a
week to figure this out.

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