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

[pratish ganguly]

Dear Jordan

When I try to restart X in the 1280x1024 resolution , if the modelines
are not specified , then the system is unable to start X. Rest all
resolutions (1024x768 and 800x600) are dispalyed fine without
modelines being specified in the xorg.conf, though the flickering
exists while changing resolution.

If I comment out the line containing the text
Option "PanelGeometry" "1280x1024"
then I am not able to change the resolution of my system. The X stays
in the same resolution that it was in earlier.

As for the display settings in BIOS, the display being used here is a
TFT Panel. There is provision for a secondary CRT display to be
attached to the system, for which the CRT option is also enabled
(though not enabled explicitly in the BIOS).

I tried out a few things in BIOS that you suggested me to do. I am
listing them out here along with the results.

1.  Tried setting the Output display to auto.(originally set to Flat
Panel, but still the xorg log file showed CRT and panel as yes )
        result: system display takes a long time to show (more than 5 minutes).

2.  Set Output display to Flat panel, in Flat Panel configuration, set
type to TFT , set resolution to 1024x768. In xorg.conf commented
"panel configuration" command. commented modeline options.
        result: system boots into 1024x768 resolution.

3.  Set Output display to Flat panel, in Flat Panel configuration, set
type to TFT , set resolution to 1280x1024. In xorg.conf commented
"panel configuration" command. commented modeline options.
        result: system unable to boot into 1280x1024 resolution. X
could not start up.

4.  Set Output display to Flat panel, in Flat Panel configuration, set
 type to TFT , set resolution to 1024x768, THEN set type to AUTO. In
xorg.conf commented "panel configuration" command. commented modeline
options.
        result: system boots into 1024x768 resolution.

5.  Set Output display to Flat panel ,  in Flat Panel configuration,
set type to TFT , set resolution to 1280x1024, THEN set type to AUTO.
In xorg.conf commented "panel configuration" command. commented
modeline options.
        result: system unable to boot into 1280x1024 resolution. X
could not start up.

6.  Set Output display to Flat panel ,  in Flat Panel configuration,
set type to TFT , set resolution to 1280x1024, THEN set type to AUTO.
In xorg.conf commented "panel configuration" command. commented all
modeline options except for 1280x1024 resolution.
        result: system boots into 1280x1024 resolution.

7.  Set Output display to Flat panel ,  in Flat Panel configuration,
set type to TFT , set resolution to 1280x1024. In xorg.conf commented
"panel configuration" command.
        result: resolution cannot be changed even if we specify them
in xorg.conf without uncommenting "panel configuration" option.

8.  Set Output display to Flat panel ,  in Flat Panel configuration,
set type to TFT , set resolution to 1280x1024. In xorg.conf
uncommented "panel configuration" command.
        result: resolution changes as specified in the xorg.conf.

9.  Set Output display to Flat panel ,  in Flat Panel configuration,
set type to TFT , set resolution to 1280x1024.  In xorg.conf commented
all modeline options.
        result: system unable to boot into 1280x1024 resolution. X
starts on all other resolutions.

10  Set Output display to Flat panel ,  in Flat Panel configuration,
set type to TFT , set resolution to 1280x1024. In xorg.conf
uncommented "panel configuration" command. uncommented modeline
options.
        result: system able to change resolution with but flickering observed.

On 12/20/07, Jordan Crouse <jordan.crouse at amd.com> wrote:
> 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

On 12/20/07, Jordan Crouse <jordan.crouse at amd.com> wrote:
> I happened to look at your log again, and I saw this:
>
> **) AMD(0): Option "PanelGeometry" "1280x1024"
>
> Make sure you take that out (and also make sure that the panel is
> disabled in your BIOS - assuming you don't have a panel attached).
>
> Jordan

With best regards
Pratish Ganguly