[Openchrome-devel] [Bug 96397] legacy modesetting removal breaks CLE266

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96397

--- Comment #15 from Kevin Brace <kevinbrace at gmx.com> ---
(In reply to Xavier Bachelot from comment #11)

Hi Xavier,

> I've reduced the needed changes to both 3d5.6b bit 7 and 3d5.6c bit 0.
> Initial registers setting is 3d5.6b = 0x84 and 3d5.6c = 0x01.
> Working registers setting is 3d5.6b = 0x04 and 3d5.6c = 0x00.
> 
> According to CX700 documentation, the older chipset with doc available :
> 
> 6b[7:6] is "First Display Channel Clock Mode Selection"
> 0x: Normal
> 1x: Division by 2
> 
> 6c[0] is "LCDCK Source Selection"
> 0: LCDCK PLL output clock
> 1: LCDCK PLL reference clock

Do you think 3X5.6C[0] is even a factor here?
LCDCK implies IGA2, but we are dealing with only IGA1 in this situation.
I suspect 3X5.6B[7:6] is suspect here.
    I know that EPIA-M BIOS has a way to specify which type of display devices
are connected to the mainboard.
What is the current setting you have?
Is it set to CRT + TV setting?
    Looking at the OpenChrome source code, it appears that division by 2 mode
is used when VT1622(A) or VT1623 are used.
However, in your case, OpenChrome appears not to be going through the VIA TV
encoder initialization code within OpenChrome.
Is this a situation where OpenChrome is not initializing the register unless
the TV encoder is actively being used, and OpenChrome is effectively depending
on the BIOS to set the register?
It is my speculation that if EPIA-M BIOS is set to CRT + TV mode, this register
field in question gets set by BIOS, but under the circumstance you have
encountered, it is not being initialized by OpenChrome.
The only exception is if you tried to use TV with OpenChrome, but when I tried
this several months ago, it caused a hang (lockup) when I connected a TV set to
EPIA-M.
However, the TV out hardware is working since the screen behaves normally when
I turn the hardware on (the stuff on the TV is cloned with the VGA out).

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