[Xorg-driver-geode] Flickering Seen On Changing Resolution

[Jordan Crouse]

On 20/12/07 10:45 +0530, pratish ganguly wrote:
> Dear Jordan
> 
> I tried without specifying any modelines at all. But in this case also , the
> fickering is seen. Moreover, in 1280x1024 pixels screer resolution, X is
> unable start up. I am attaching the X log file along with this mail.

The X log indicates that your BIOS is telling it that you have a TFT panel
attached via the flat panel interface, as well as a CRT attached via the
VGA connector.  Is that true?  If so, then the reason for your flickering
is that we are trying to drive both a panel and a CRT simultaneously.
In that case, the TFT is more strict about its timings, so we have to choose
the timings for the TFT which don't look very good on a
CRT unless they are very carefully chosen.

If you _do not_ have a TFT panel attached, then please go into your BIOS 
and turn off TFT panel support.  That will give the driver a much wider
range of modes to choose from.

I've said this before, but it doesn't hurt to repeat it.  Unfortunately,
we don't have any way to tell if a TFT pane; is physically attached.  The
driver is told either by the BIOS (or on LinuxBIOS and OFW the
PanelGeometry option) if a panel is attached, and what the geometry
is (width, height, refresh rate).  If we think that a panel is attached,
then we will go into simultaneous mode automatically (because if a panel 
_is_ attached, then the wrong timings will damage it).

So if you do not have a panel please go into your BIOS and make sure
that TFT support is disabled.  Also make sure that you are not using
the PanelGeometry option.

If you are in doubt if a panel is being detected or not, open up your
log and look for this (this is a direct copy from Pratish's mail):

(II) AMD(0): LX output options:
(II) AMD(0):  CRT: YES
(II) AMD(0):  PANEL: YES
(II) AMD(0):  VGA: YES

If PANEL is YES and you don't have a panel, then please, disable it.

Thank you,
Jordan