Problem with replacement display

[Jon Senior]

Hi,

I swapped out the LCD panel in my Thinkpad T60 today to resolve a
backlight issue (pink tint). The new display works fine, X seems to
detect it OK, but when I plug in my external monitor it all goes wrong.
When xrandr starts probing, the internal panel loses the picture. The
backlight remains on, and according to xrandr I should have an image,
but the screen remains black. xrandr reports the exact same resolutions
for both displays, although the internal one 1024x768 and the external
one 1280x1024.  The chip is a Mobility Radeon x1300, the new panel is a
like-for-like replacement (or as close as they ever get in laptop
world!). The lines below appear in Xorg.0.log (sadly I don't have a
backup of a log file pre-dating the upgrade so I can't compare (And I
don't fancy taking the laptop screen apart again!).

They appear to show that the graphics chip is failing to retrieve the
EDID information from the internal LCD and using either some internal
default (with no external device) or the data from the external device
(when connected).

Any ideas? Any suggestions?

Jon Senior

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(II) RADEON(0): Output VGA-0 has no monitor section
(II) RADEON(0): I2C bus "VGA-0" initialized.
(II) RADEON(0): Output LVDS has no monitor section
(II) RADEON(0): I2C bus "LVDS" initialized.
(II) RADEON(0): Output DVI-0 has no monitor section
(II) RADEON(0): I2C bus "DVI-0" initialized.
(II) RADEON(0): Port0:
  XRANDR name: VGA-0
  Connector: VGA
  CRT1: INTERNAL_KLDSCP_DAC1
  DDC reg: 0x7e40
(II) RADEON(0): Port1:
  XRANDR name: LVDS
  Connector: LVDS
  LCD1: INTERNAL_LVTM1
  DDC reg: 0x7e40
(II) RADEON(0): Port2:
  XRANDR name: DVI-0
  Connector: DVI-I
  DFP1: INTERNAL_KLDSCP_TMDS1
  DDC reg: 0x7e50
(II) RADEON(0): I2C device "VGA-0:ddc2" registered at address 0xA0.
Dac detection success
(II) RADEON(0): Output: VGA-0, Detected Monitor Type: 0
finished output detect: 0
(II) RADEON(0): I2C device "LVDS:ddc2" registered at address 0xA0.
(II) RADEON(0): Output: LVDS, Detected Monitor Type: 2
finished output detect: 1
(II) RADEON(0): I2C device "DVI-0:ddc2" registered at address 0xA0.
(II) RADEON(0): Output: DVI-0, Detected Monitor Type: 0
Unhandled monitor type 0
finished output detect: 2
finished all detect
before xf86InitialConfiguration
Dac detection success

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