Nov 22, 2014 - 09:02pm
I am having a strange VGA output problem. I recently installed Ubuntu 14.04 (64 bit) on hp elitebook 840 g1. I connected my laptop to an external monitor which has full HD option. Everything was working fine. Then suddently the power to my external monitor got disconnected and I switched the display to the laptop (using Fn + F4).
After that I have not been able to get the display to the external monitor. In fact when I try to boot my laptop with the external monitor being connected, the external monitor briefly displays the contents. The external monitor shows the display till I login. But once I have logged in, the external monitor goes blank.
So after logging in, the system is not able to identify the external monitor. In fact, when I click on displays in the system settings, it only shows the "Built-in Display" of the laptop.
It seems that once I have switched to the laptop display, the external monitor is not being recognized at all.
For clarity, I am showing you the output of lshw -C video:
$ sudo lshw -C video
description: VGA compatible controller
product: Haswell-ULT Integrated Graphics Controller
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
width: 64 bits
capabilities: msi pm vga_controller bus_master cap_list rom
configuration: driver=i915 latency=0
resources: irq:65 memory:d0000000-d03fffff memory:c0000000-cfffffff ioport:3000(size=64)
I found a temporary fix for this problem. I deleted ~/.config/monitor.xml file and restarted. Everything is properly displayed on the external monitor now.
But this is just a temporary fix. If I switch the display back to the laptop using (Fn + F4) commands, I again have the same problem. The system then stops detecting the external monitor. So I can not again switch to it :-(!