Re: Regression: radeonfb: No synchronisation on CRT with linux-2.6.13-rc5

[Kyle Moffett <mrmacman_g4@mac.com>]

On Aug 7, 2005, at 12:13:38, Benjamin Herrenschmidt wrote:
>> I've got an LCD, and on mine
>> it looks like every third pixel-line gets shifted about 32-64  
>> pixels to
>> the left, and they move with display refresh.  My guess is that
>> something is interrupting radeonfb during a critical time in display
>> syncing and forcing the video card to wait too far into the next line
>> before sending pixels.
>
> radeonfb is mostly inactive after it has setup the framebuffer and
> unless you actually draw something, in which case, accel code is  
> called.
>
> _However_ there is an unrelated problem with some panels, including  
> some
> of the 17": The panel doesn't always "sync" properly. This seem to be
> related to some subtle timing issue in the LVDS code but I don't know
> exactly what yet. You can usually get it back by repeately turning the
> backlight all the way down (which shuts the panel off) and back up  
> until
> it "catches".

Hmm.  This doesn't really fit as my issues are very reproducible.  The
behaviour under stock Debian 2.6.8 is identical during reboots and after
fblevel 0 ; sleep X ; fblevel 15.  Likewise, stock 2.6.11, 2.6.12.4, and
2.6.13-rc5, although I'm just getting back to testing things.

Cheers,
Kyle Moffett

--
There are two ways of constructing a software design. One way is to  
make it so
simple that there are obviously no deficiencies. And the other way is  
to make
it so complicated that there are no obvious deficiencies.  The first  
method is
far more difficult.
   -- C.A.R. Hoare




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