[Openchrome-devel] [Bug 101395] Color banding with OpenChrome driver V0.6.133

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=101395

--- Comment #4 from Kevin Brace <kevinbrace at gmx.com> ---
(In reply to Marty from comment #3)

Hi Marty,

> Hi Kevin,
> 
> Yes. This is exactly what I see! I even downloaded from Internet the
> original Lubuntu 12.04 wallpaper to do a closer analysis of the number of
> color steps in the image. It is identical to what you uploaded. So I can say
> everything looks like being in a 16 bit color mode.
> 
> Cheers,
> Marty

Okay, at least for 16-bit color mode, I have known this issue for a while, but
there are reasons why I had to live with this flaw for OpenChrome DDX Version
0.6.
Prior to OpenChrome DDX Version 0.5 or 0.6, 16-bit color mode was broken if
gamma correction hardware was turned on.
Turning on gamma correction was the reason why the colors went nuts in 16-bit
mode, so I had to turn it off.
16-bit color mode is still useful in some cases, especially one wants to use
dual head mode with left and right screen (As I have discussed previously, due
to hardware limitations, you will need to use 16-bit color mode if one wants to
use 2 monitors side by side.).
At the end of the day, since I am the only one who gets to decide what goes
into the code (because I am pretty much the only person on this planet that
spends so much time in trying revive old, abandoned graphics device drivers), I
had to make tradeoffs, and since there had to be a new version of OpenChrome
released at some point, I had to ship a new version with this color gradient
flaw.
My goal of OpenChrome development has always been to improve the quality of the
code since Day One (sometime around mid-2015), and as far as I am concerned,
the code is gradually getting to where it should be (i.e., The latest
improvement in how display devices are detected which fixed the standby resume
issue with your laptop's 24-bit FP interface to a VIA LVDS bridge chip.).
    Like the previous bug I have effectively fixed (i.e., standby resume 24-bit
FP interface FP restoration bug), it might take a while for me to figure out
how to fix the problem.
Since I practically do not use Lubuntu 14.04 at all, if you do not mind keeping
Lubuntu 12.04 for now (until I fix the bug), that will be appreciated.
That being said, I tried the 16-bit color mode on Xubuntu 14.04 yesterday, and
I did observe the same color gradient issue I saw on Lubuntu 12.04.
I will revisit what I did with the color palette and gamma control many months
ago.
I think it will take a while to fix this issue, and I will also have to
continue to devote some time to modernize the current OpenChrome DDX code so
the code developed for OpenChrome DDX can be effectively shared with OpenChrome
DRM.

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