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

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Mon Nov 2 21:43:39 PST 2015


--- Comment #53 from Kevin Brace <kevinbrace at gmx.com> ---
Hi Benno,

(In reply to Benno Schulenberg from comment #48)
> One obvious fix is suggested by the code itself.  See attached patch.

I reviewed the patch, and I find it unlikely the patch will make any material
difference in the behavior.
Why can I say this?
It is because the unpublished code I wrote between July and early September
touched upon the very code path your patch addresses.
That particular function you are applying the patch apparently deals with
standby / hibernation resume extended VGA register restoration.
I completely rewrote this section, but at least in my case, it did not alter
the behavior of OpenChrome on VN896 chipset (i.e., LCD screen state restoration
after ACPI S3 State resume).
I believe the patch will likely add 150 to 200 lines of code to OpenChrome.
The code I wrote is still not available as a patch due to the fact that I am
still learning how to create a patch in the first place (i.e., I am a first
time developer.), but also Xavier did not really like the other modifications I
made to OpenChrome (i.e., Some of what he suggested were reasonable, so I will
comply with most of his wishes.). 
The code I wrote saves all known published extended VGA registers, however, it
does not save VX900 DisplayPort registers at this point (VX900 HDMI registers
appears to be unpublished.).
Other than that, the code I wrote appears to work, and doesn't crash the system
when the computer resumes, but LCD screen is still getting lost.
Based on this, the bug is likely located in via_ums.c.
I will start analyzing this module soon.

> Small patches that fix one specific issue are much more likely to get
> accepted.

I am planning to create 2 patches soon.

> Did you send it to the mailing list too?  It's much better to have things in
> the open: seeing things happen can trigger someone into helping.

I can provide the code in the form of a patch after I figure it out how to do
If you know how to do it, it will be nice if you can share the instructions on
how to do this.
The way I did it is,

$ diff -cr (Original Files Directory) (Modified Files Directory)

If there is a better way to create a patch, let me know.


Kevin Brace

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