Using arandr, or KDE's RandR manager, I'm trying to adjust my display to stretch across 3 monitors. One of the monitors enters power-saving mode when I try this. Monitors are, from left to right:
DVI-1 (1680x1050 LCD)
DisplayPort-1 (1920x1080 LCD)
DVI-0 (1680x1050 LCD)
Configuring a desktop with all monitors set to their maximum resolution causes one of the two DVI-connected monitors to enter power-saving mode. The mouse cursor will still "disappear" into this monitor as if it were enabled. No error messages appear in either X.org.log or dmesg. It is non-deterministic as to which monitor turns off of the two DVI-connected monitors.
I can configure a desktop with, for example, 1280x1024, 1920x1080, 1280x1024 for resolutions (left to right) and all three monitors will function properly. I cannot use 1680x1050, 1280x1024, 1680x1050, as one of the DVI monitors will enter power saving mode.
I have tested, and this hardware configuration will function with the proprietary fglrx driver, and under Windows, so the card/monitors do not appear at fault.
I have tried the 2.6.38 release candidate kernels, and this feature has never functioned correctly, so I don't think it's a regression.
Asus M4A89/GTD-PRO USB3
DVI-1: LG Flatron W2242TQ
DisplayPort-1: Dell UV22H
DVI-0: ASUS (unknown)
ArchLinux, 64-bit with:
Please let me know if I can provide any additional details. I am willing to apply patches to the kernel or other packages as needed to test.
I've experimented further with RandR, and I've found some additional information:
A configuration of 1680x1050,inactive,1680x1050 does function correctly.
At boot, with KMS enabled, two of my three displays are active when the radeon module loads: DisplayPort-1 and one of the two DVI displays.
If I use ctrl+alt+f1 to switch back to a console when I have my display configured to use DVI-1 and DVI-0, one of the DVI displays will enter power saving mode and DisplayPort-1 will turn back on. If I then use ctrl+alt+f7 to re-enter my desktop, DisplayPort-1 turns off leaving only one of the two DVI displays enabled.
I'm also having trouble coming up with consistent use cases, as behaviour is not consistent. For example, I have tried configuring 1280x1024,1280x1024,1280x1024 for my displays, and have received inconsistent results; sometimes all displays function, other times I have had one of the three displays (including DisplayPort-1) enter power-saving mode.
DisplayPort-1 is actually a U2211H, not UV22H
Results are still repeatable, using updated software stack as follows:
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