[i945] D945GCLF & Panasonic TV - X resolution too high resulting in black TV screen

[Neil Jeffery]

This is a regression, since it used to work before upgrading to 8.10.

I recently upgraded to 8.10 and now I am faced with a black screen on boot (I still hear the Ubuntu Drums). I can access the vty terminals and login etc so I know the machine hasn't crashed.

The hardware I am running is:

D945GCLF - Atom Board with on board Graphics
TH-42PZ80B - Panasonic Plasma TV

Adding the following line to xorg.conf fixes the issue
Option "PreferredMode" "1360x768"

[Dimitrios Symeonidis (azimout)]

the product has the intel 945 graphics chip:
http://www.intel.com/Products/Desktop/Motherboards/D945GCLF/D945GCLF-overview.htm

[Dimitrios Symeonidis (azimout)]

can you please clarify: do you still see the grub menu?
also, please attach your /etc/X11/xorg.conf

[Neil Jeffery (neilneil2000)]

I have tried 3 xorg.conf files...here they are:

[Neil Jeffery (neilneil2000)]

I can confirm grub displays as expected and I can use the virtual terminals when ubuntu has loaded

[Dimitrios Symeonidis (azimout)]

neil, can you please also try without any xorg.conf? thank you
also, you could try playing around with "dpkg-reconfigure xserver-xorg -phigh"

[Neil Jeffery (neilneil2000)]

Sorry for not mentioning this in my original post. I have tried both of these methods a few times but the xorg.conf file is always rebuilt as the attached xorg.conf3.txt

[Dimitrios Symeonidis (azimout)]

can you attach it to a normal monitor? i suspect that it will display properly...
does the plasma tv have any special vga input requirements?

[Neil Jeffery (neilneil2000)]

I will try it with a standard monitor when I get a chance. I suspect it will work too, but as I said it worked with the TV previously.

Here is the manual for the TV and as far as I can see it supports standard VGA inputs.

http://dlc.panasonic-europe-service.com/EUDocs/GetDoc.aspx?did=159842&fmt=pdf&lang=en&src=3&uilang=en&cbAccept=on&go=View

I think it could be something to do with the messaging between the TV and graphics card so say what resolutions are supported...I did know what that was called once upon a time!

[Neil Jeffery (neilneil2000)]

I can confirm that when a standard monitor is attached the screen works as expected with no problems. I did notice however that the actual installed OS is "Mythbuntu" I am going to format the hard drive and install Ubuntu to if this alleviates the problem

[Neil Jeffery (neilneil2000)]

I have now down a complete reinstall of with Ubuntu 8.10 Server Edition.

This worked without issue.

I then ran

sudo apt-get install ubuntu-desktop

At boot and shutdown I see the ubuntu Logo with the progress bar but the screen is blank when the machine is fully powered on. Ctrl+Alt+F# gives me the correct terminals and that works fine

However, if I ssh into the machine with the -Y flag (enable X11 forwarding) then I can run X programs without issue.

[Dimitrios Symeonidis (azimout)]

i should have asked this from the beginning:
could you please attach the x server log? it can be found under /var/log/Xorg.0.log
thank you

[Neil Jeffery (neilneil2000)]

Here is the log file as requested

[Dimitrios Symeonidis (azimout)]

hmmmm, no errors there... switching back to new...

[Neil Jeffery (neilneil2000)]

Is there anything I can add to help out here?

[Neil Jeffery (neilneil2000)]

I may be wrong but I have a feeling that the line

(II) intel(0): Setting screen physical size to 304 x 228

Is something to do with the problem. I expect this lies outside the accepted input range on the TV and thus is showing up as black.

Is there anyway I can force the resolution to see if this is the case?

[Neil Jeffery (neilneil2000)]

I have been playing with John Fremlin's "read-edid". And it looks like the TV is not responding the the EDID call by the PC. I expect this is what is causing all the problems!

Here is the output:

./get-edid | ./parse-edid
./parse-edid: parse-edid version 1.4.1
./get-edid: get-edid version 1.4.1

 Performing real mode VBE call
 Interrupt 0x10 ax=0x4f00 bx=0x0 cx=0x0
./parse-edid: IO error reading EDID

This tallies with my previous comment, and I need a way to force the output resolution and tell Xorg not to bother with EDID. I know you could do this with previous xorg versions, by editing the xorg.conf file, but since this has been somewhat deprecated, I'm not sure how to test this.

[Dimitrios Symeonidis (azimout)]

yes, read-edid 1.4.1 is broken, it doesn't read my monitor either...
someone else took over maintaining the package and released a version 2.0.0, which hasn't made it into ubuntu yet...
https://bugs.launchpad.net/ubuntu/+source/read-edid/+bug/242043/comments/2

anyway, xorg doesn't call the read-edid tool to find out the monitor's capabilities, so I don't think that's at fault... however, you might be on the right path, in the sense that the resolution might be the problem

to set the screen resolution, just call gnome-display-properties...

[Neil Jeffery (neilneil2000)]

Unfortunately I cannot use gnome-display-properties as I am faced with a black screen.

However...I have in the meantime solved the problem with the help of the nice people on the X.org IRC channel (Many thanks mzz & gami)

It turns out that X was trying to output a resolution of 1152x864, which is not supported by my screen.

I have added the line

Option "PreferredMode" "1360x768"

to my xorg.conf file and now it works.

However they tell me that this is still a bug and is something that needs to be fixed in X

[Dimitrios Symeonidis (azimout)]

setting to triaged, importance high, and reassigning to the xorg package
added the regression-release tag, as per https://wiki.ubuntu.com/QATeam/RegressionTracking

[Bryce Harrington (bryce)]

Hi Neil,

Have you had a chance to test this against the Jaunty release?

It sounds like the issue is a monitor capabilities-detection issue rather than a bug in -intel itself (so I'm reassigning), however a newer version of that driver is available at this PPA: https://edge.launchpad.net/~ubuntu-x-swat/+archive/x-updates/

Meanwhile, you can capture a dump of what X is parsing for EDID via this command (which requires X be running, but you can run it from a vt console): 'DISPLAY=:0 xrandr --verbose' - this info will be useful in case the monitor has to be quirked.

Also run 'sudo ddcprobe > ddcprobe.txt' to get the DDC info, which may be what X is using instead of EDID.

The output of 'lspci -vvnn > lspci-vvnn.txt' could also be useful.

For more info on analyzing this type of problem, please see https://wiki.ubuntu.com/X/Troubleshooting/Resolution

[Bryce Harrington (bryce)]

We're closing this bug since it is has been some time with no response from the original reporter. However, if the issue still exists please feel free to reopen with the requested information. Also, if you could, please test against the latest development version of Ubuntu, since this confirms the bug is one we may be able to pass upstream for help.