How to properly handle double-width framebuffer?

[Chetan Raj]

We have a LCD display panel whose real physical dimensions are of ratio
4:3.  However, the panel only accepts framebuffer of resolution 640x240
(8:3).

I would like to display an image of dimension 320x240 (4:3) pixels
completely over the display panel. However, currently the image covers only
right half of the screen.

How do we properly handle the above scenario in Xorg?  How do we effectively
double the x-width so that a 4:3 image is displayed properly on a 4:3
physical dimension device that internally uses 8:3 pixel ratio resolutions?

It would also be helpful if anyone can throw light on such a strange LCD
panel configuration that has 4:3 physical dimension, but uses 8:3 pixel
ratio.


Xorg version details are:

X.Org X Server 1.7.1
Release Date: 2009-10-23
X Protocol Version 11, Revision 0

fbdev device.

my xorg.conf file:

Section "Device"
    Identifier  "chetFBDevice"
    Driver      "fbdev"
EndSection

Section "Monitor"
    Identifier "chetMonitor"
EndSection


Section "Screen"
    Identifier "Screen0"
    Device     "chetFBDevice"
    Monitor     "chetMonitor"
    DefaultDepth 24
    SubSection "Display"
        Depth 8
    EndSubSection
    SubSection "Display"
        Depth 24
    EndSubSection
EndSection


Xorg,0.log message:

(II) FBDEV: driver for framebuffer: fbdev
(WW) Falling back to old probe method for fbdev
(II) Loading sub module "fbdevhw"
(II) LoadModule: "fbdevhw"
(II) Loading /opt/xorg/lib/xorg/modules/linux/libfbdevhw.so
(II) Module fbdevhw: vendor="X.Org Foundation"
    compiled for 1.7.1, module version = 0.0.2
    ABI class: X.Org Video Driver, version 6.0
(II) FBDEV(0): using default device
(WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
(II) Running in FRAMEBUFFER Mode
(**) FBDEV(0): Depth 24, (--) framebuffer bpp 32
(==) FBDEV(0): RGB weight 888
(==) FBDEV(0): Default visual is TrueColor
(==) FBDEV(0): Using gamma correction (1.0, 1.0, 1.0)
(II) FBDEV(0): hardware: fb (video memory: 600kB)
(II) FBDEV(0): checking modes against framebuffer device...
(II) FBDEV(0): checking modes against monitor...
(--) FBDEV(0): Virtual size is 640x240 (pitch 640)
(**) FBDEV(0):  Built-in mode "current"
(==) FBDEV(0): DPI set to (96, 96)
(II) Loading sub module "fb"
(II) LoadModule: "fb"
(II) Loading /opt/xorg/lib/xorg/modules/libfb.so
(II) Module fb: vendor="X.Org Foundation"
    compiled for 1.7.1, module version = 1.0.0
    ABI class: X.Org ANSI C Emulation, version 0.4
(**) FBDEV(0): using shadow framebuffer
(II) Loading sub module "shadow"
(II) LoadModule: "shadow"
(II) Loading /mtd_rwarea/opt/xorg/lib/xorg/modules/libshadow.so
(II) Module shadow: vendor="X.Org Foundation"
    compiled for 1.7.1, module version = 1.1.0
    ABI class: X.Org ANSI C Emulation, version 0.4
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