[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 #279 from Kevin Brace <kevinbrace at gmx.com> ---
(In reply to Christopher from comment #278)

Hi Christopher,

> Pardon me for not mentioning it sooner -- but rcrsn51 -- who made that HowTo
> -- has also made one for a utility of his, called "ISOBooter".
> 
> That HowTo is here, you will probably need actual bash to run it (IIRC
> Ubuntu defaults to dash, which is of course different) --
> http://www.murga-linux.com/puppy/viewtopic.php?t=67235
> 
> My humblest apologies for not being more active lately, I'm still trying to
> get that script working, and -- aside from that -- I've been struggling with
> some IRL stuff, plus my mother's birthday is in less than a week!
> 
> Worth noting, though -- my most recent attempt was using a USB flash
> drive... I seem to recall stating that fairly clearly, although I could be
> wrong as I have not looked back through the comments to check. I can't
> imagine what the difference would be to the OS... a filesystem is a
> filesystem is a filesystem -- or so I'd think...
> 
> Also, again, Precise 5.7.1 is KNOWN WORKING prior to this issue being raised
> -- as it has an older (pre-0.3.x) version of openchrome. The problems do not
> start until TahrPup / Ubuntu Trusty Tahr 14.04. I have independently
> verified, through accident in fact, that this is true of at least two Ubuntu
> derivatives -- Linux Mint "Rosa" will bring up a desktop using the "vesa"
> driver, but as left-click crashes and restarts the WM, it's not functional.
> Linux Lite won't even bring up a desktop; it crashes similar to TahrPup --
> black screen, no text -- but I couldn't extract enough useful information
> out of them to do anything meaningful; their devs don't care to mingle with
> the common folk (sadly) which means a lot of people are stranded without
> real answers. The best advice I got was "use this version that's more than
> one major revision behind" which is, when you think about it, a little daft.
> 
> I'll retest --again, from flash drive-- later, but I really don't see that
> being much of a difference from the SD card. Which I still have to order a
> replacement of... ugh...

Yes, I do understand that OpenChrome that came with Precise Puppy 5.7.1 was
working when you reported the bug.
The thing is, the code I have been working with for the past few months and the
code that was used in OpenChrome Version 0.2.904 are totally different.
When James Simmons (the OpenChrome developer who pretty much did most code
commits for the past 5 years) released OpenChrome Version 0.3.0, he totally
rewrote the code, in order to support KMS (Kernel Mode Setting), in addition to
the traditional UMS (User Mode Setting).
Just for your basic knowledge if you are not familiar with this KMS and UMS
lingo, in KMS, the DRM module (Direct Rendering Manager) handles screen mode
setting.
KMS support was added in Linux kernel 2.6.28 if I am correct (only supported
Intel IGP at the time) and ATI Technologies / AMD Radeon KMS support was added
in Linux kernel 2.6.29.
Looking at both OpenChrome and the newer KMS supporting DRM module, it appears
that most of James' development resources (i.e., time) went towards
implementing the KMS supporting DRM module.
The code I have been struggling with is what is called UMS.
In UMS, display mode setting code in inside OpenChrome itself (i.e.,
openchrome_drv.so).
    I do know several previous developers are not happy when I write anything
that appears mildly critical of them (I guess it is a sensitive issue to
them.), but that being said, James definitely broke the display detection code
when he rewrote the code for OpenChrome Version 0.3.x.
He assumed that only I2C bus 1 is used for VGA detection.
In addition to this, Xavier Bachelot made some changes to the code where
OpenChrome was no longer detecting "analog" type interfaces (i.e., VGA
interface).
This is why the VGA coming from DVI to VGA adapter worked with Version 0.2.9xx,
but not with Version 0.3.3.
OpenChrome Version 0.3.3 code was no longer probing I2C bus 2 for VGA
detection, in addition to not looking for an analog type interface, and that is
the root cause of the problem.
It appears that OpenChrome "happened" to probe I2C bus 2 for VGA monitor in
Version 0.2.9xx, but my personal opinion is that it just happened to work (I do
not think it was that well written.).
    What I am trying to do now is, I am trying to rewrite the display detection
completely (i.e., but not from the ground up, as that will take too much time),
and hopefully that will result in a more reliable code.
This is why I removed the "rot" from the code recently, as this stuff was
getting in my way of rewriting the code.
I personally did not want to do this much code rewriting at this point since I
wanted to release OpenChrome Version 0.3.4 quickly, but at this point, I feel
like I will be in for the long haul (i.e., several months) before I can release
a new version.
I will likely call this OpenChrome Version 0.4.0, and will likely cancel
Version 0.3.4.

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