[Gutsy] screens and graphics resolution of screen 2 affects resolution of screen 1

[DFreeze]

Binary package hint: displayconfig-gtk

When adding a screen to Screens and Graphics with a resolution different to my laptop's (1440x900), the resolution of my laptop screen changes too (using mirror option). When rebooting I couldn't get GDM back up, and had to resort to dpkg-reconfigure xserver-xorg to get my resolution back (see my bugreport on failsafe x for that).

[TerryG (tgalati4)]

Thanks for your bug submission. If you have Intel graphics chip, you may be limited to 2048x2048 pixel size for both screens combined. It's a known limitation for Intel chipset. What graphics card do you have? How much video RAM? If shared, how much devoted to video?

Marking as Incomplete pending more details.

At least you know how to get your screen back.

[DFreeze (dfreeze)]

           *-display UNCLAIMED
                description: VGA compatible controller
                product: Radeon XPRESS 200M 5955 (PCIE)
                vendor: ATI Technologies Inc
                physical id: 5
                bus info: pci@0000:01:05.0
                version: 00
                width: 32 bits
                clock: 66MHz
                capabilities: pm vga_controller bus_master cap_list
                configuration: latency=64 mingnt=8

It has 128 MB of shared memory, and xorg.conf sais only this about my video:

Section "Device"
 Identifier "Configured Video Device"
EndSection

So I'm using the default ATI driver.

Can it be that the mirror option has to use the smallest available resolution, or should it scale automatically. The TV screen has a 1366 x 768 resolution.

[TerryG (tgalati4)]

In a terminal:

>envy

or

>sudo envy

(I can't remember if you need sudo permissions for this.)

See if there are restricted drivers. The open source (reverse-engineered) drivers for ATI have limited capability. Once you get the restricted drivers going, then start playing with resolutions. Backup your configuration file first (sudo cp /etc/X11/xorg.conf /etc/X11/xorg.bak).

You want to address the TV at it's native resolution (1366 by 768). Be mindful that your graphics chip may not support all refresh rates--in other words, when you select TV resolution, that clock setting will be unique and the PC is left with using an even-multiple of that clock setting. This will sometimes result in strange resolutions for the PC monitor. This is something most people don't understand. You can address either the TV or Monitor at it's native resolution, but not both at the same time. Unless you have a high-end graphics card. I'm not sure what the capabilities of the ATI Radeon Xpress 200M are, but you will find out it's limitations soon enough.

Leaving as Incomplete pending ATI restricted driver tests.

[DFreeze (dfreeze)]

I did a test using the fglrx driver. This time the TV resolution didn't want to play ball and big black rims were put around the image. But you're right, I didn't know about the even-multiple restrictions - although it sounds perfectly obvious. My graphics card is a very low-spec mobile card, so I suspect this mechanism to cause the unsuspected behaviour. Thanks for explaining! I think that comment alone made this bugreport fit for closing - it's not a bug, it's a feature (or rather lack of a feature)...

[Bryce Harrington (bryce)]

Thank you for reporting this bug and for your efforts to make
Ubuntu better. As Xorg has improved this past year, an unfortunate side
effect of these improvements is that it has rendered several design
assumptions in displayconfig-gtk obsolete. So, starting with Hardy we
are no longer putting displayconfig-gtk forth as a primary configuration
tool, and are putting our development focus into the Screen Resolution
applet. As a result, we do not plan to fix this bug and thus are closing
it.

For more background on this change, please see this page:
https://wiki.ubuntu.com/X/DisplayConfigGtk