It's an old but still serviceable laptop - Compaq Evo N1020v

All I want is for the external VGA-attached monitor to duplicate the content of the built-in laptop screen. If I boot Windows XP it all works as expected. If I boot Linux (I've tried many distros, old releases and new) the BIOS info and the GRUB menu display fine, but then (I guess when XORG starts) the external monitor goes blank and stays blank.

In "Monitor Settings" I can specify that both screens display the same image, but it doesn't change anything.

"lshw" says...
*-display
description: VGA compatible controller
product: RS200 [Radeon IGP330M/340M/350M]
vendor: Advanced Micro Devices [AMD] nee ATI
physical id: 5
bus info: pci@0000:01:05.0
version: 00
width: 32 bits
clock: 66MHz
capabilities: agp agp-2.0 pm vga_controller bus_master cap_list rom
configuration: driver=radeon latency=66 mingnt=8
resources: irq:5 memory:f8000000-fbffffff ioport:a000(size=256) memory:f0300000-f030ffff memory:f0320000-f033ffff

and "xrandr" says...
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 4096 x 4096
VGA-0 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1024x768 60.0*
800x600 60.3 56.2
848x480 60.0
640x480 59.9
LVDS connected 1024x768+0+0 (normal left inverted right x axis y axis) 304mm x 228mm
1024x768 47.5*
800x600 59.9
848x480 59.7
720x480 59.7
640x480 59.4
S-video disconnected (normal left inverted right x axis y axis)


sudo dmidecode -t 1; uname -a
says...
# dmidecode 2.11
SMBIOS 2.3 present.

Handle 0x0001, DMI type 1, 25
bytes
System Information
Manufacturer: Compaq
Product Name: Evo
N1020v
Version: 0100
Serial Number: 9X34LDLZV4XT
UUID:
80E14CBC-C163-0010-9EAE-23CD071A931C
Wake-up Type: Power Switch

Linux
Evo-N1020v-1 3.5.0-22-generic #34-Ubuntu SMP Tue Jan 8 21:41:11 UTC 2013
i686 i686 i686 GNU/Linux

So it seems the hardware is recognised, but perhaps the radeon driver needs to be told to look for the external display?

Can anyone see what I need to do?

Gordon Hay

If you change the xorg.conf, you have have to restart X to use the updated config. If the second display is not ON when X starts then X cannot check the EDID information of the monitor to determine it's display settings.

$ xvidtune -show

If you have dual displays, cloned or not, you should have an entry for each display. Or I could be wrong.

External display IS on when X starts: BIOS and GRUB have already found it OK by then...
Other Linux laptops (with different video hardware) find & use the same external display with no trouble...

And the output of xvidtune shows one display?

Any hints in /var/log/Xorg.0.log ?

It's possible that the Hsync / Vsync values assumed are wrong and everything is there, just not in a way that the display can show it.

The output of "xvidtune -show" is:
"1024x768" 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync

As for Xorg.0.log, nothing hits me as obviously wrong, but then I don't really know what I'm looking at. It does include:
ABI class: X.Org Video Driver, version 14.1
RADEON(0): Depth 24, (--) framebuffer bpp 32
RADEON(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps)
RADEON(0): Default visual is TrueColor
RADEON(0): RGB weight 888
RADEON(0): Using 8 bits per RGB (8 bit DAC)
RADEON(0): Chipset: "ATI Radeon IGP330M/340M/350M (U2) 4337" (ChipID = 0x4337)
Output VGA-0 using monitor section Configured Monitor
RADEON(0): Output LVDS has no monitor section
RADEON(0): Output S-video has no monitor section
RADEON(0): EDID for output VGA-0
RADEON(0): Not using mode "848x480" (hsync out of range)
RADEON(0): Printing probed modes for output VGA-0
RADEON(0): Modeline "1024x768"x60.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz e)
RADEON(0): Modeline "800x600"x60.3 40.00 800 840 968 1056 600 601 605 628 +hsync +vsync (37.9 kHz e)
RADEON(0): Modeline "800x600"x56.2 36.00 800 824 896 1024 600 601 603 625 +hsync +vsync (35.2 kHz e)
RADEON(0): Modeline "640x480"x59.9 25.18 640 656 752 800 480 489 492 525 -hsync -vsync (31.5 kHz e)

RADEON(0): Not using mode "848x480" (hsync out of range)

I'm not sure if that means anything. But you might try setting a resolution in xorg.conf plus Virtual or however that was triggered. Or try to set the default for the main display to one supported by the other monitor aka Modes "". Going 640x480 is a good bet on most NTSC (american) displays. Basically get something to work first. Then try to get what you actually want to work.

Normally the (WW) or (EE) as in warning or error lines are the ones you should look for in Xorg.0.log. Although out of range hsync / vsync aka HorizSync / VertRefresh wont throw any errors. As the setup is valid for the graphics card, even though the monitor cannot use it to show the result. Monitors generally have EDID to tell X what it's capabilities are, but some monitors have incorrect EDID information.

I've just discovered that...
- if I add "nomodeset" to the standard Lubuntu boot parameters, the external display is found, but only in 640x480 mode
- but if I boot in Lubuntu Recovery Mode, the the external display is found and works as I'd expect

Does this give anyone a clue as to why it wouldn't work in a normal boot?