Green screen with color depth of 16 bits

I have run into a problem with the openchrome driver, when used with color depth of 16 bits. With the default depth of 24 bits everything works ok, but with color depth of 16 bits the screen is mostly green.

The driver seems to be otherwise useable. It is possible to correct the color problem somewhat with xgamma, but this does not really help the broken appearance. However, the hardware cursor appears to have the right colour.

I have tried various Xorg settings relating to EXA and such, but can not find a combination that would make a change for the better. Switching to a software cursor changes cursor color to a greener tint.

My main motivation to get this to work is that there are some thin client hardware that should be very much useable with LTSP, and there is a remarkable speed difference when colour depths of 16 and 24 are used (16 being of course faster).

Here is the lspci output for one machine in question:

--
00:00.0 Host bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge (rev 10)
00:00.1 Host bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge
00:00.2 Host bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge
00:00.3 Host bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge
00:00.4 Host bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge
00:00.7 Host bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge
00:01.0 PCI bridge: VIA Technologies, Inc. VT8237/VX700 PCI Bridge
00:08.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)
00:0f.0 IDE interface: VIA Technologies, Inc. VX800 Serial ATA and EIDE Controller
00:10.0 USB controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 90)
00:10.1 USB controller: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller (rev 90)
00:10.4 USB controller: VIA Technologies, Inc. USB 2.0 (rev 90)
00:11.0 ISA bridge: VIA Technologies, Inc. CX700/VX700 PCI to ISA Bridge
00:11.7 Host bridge: VIA Technologies, Inc. CX700/VX700 Internal Module Bus
00:13.0 PCI bridge: VIA Technologies, Inc. CX700/VX700 Host Bridge
01:00.0 VGA compatible controller: VIA Technologies, Inc. CX700/VX700 [S3 UniChrome Pro] (rev 03)
02:01.0 Audio device: VIA Technologies, Inc. VT8237A/VT8251 HDA Controller (rev 10)
--

On Lucid (10.04) and Precise (12.04) this machine/configuration works properly. I can only reproduce the problem in Quantal (12.10).

$ lsb_release -rd
Description: Ubuntu 12.10
Release: 12.10

$ apt-cache policy xserver-xorg-video-openchrome
xserver-xorg-video-openchrome:
  Installed: 1:0.3.1-0ubuntu1
  Candidate: 1:0.3.1-0ubuntu1
  Version table:
 *** 1:0.3.1-0ubuntu1 0
        100 /var/lib/dpkg/status