What's the status of multi-monitor support in Linux, kernel 3.10 and later ?


#1

Hi guys,
what is the status of multi-monitor support in recent Linux distros? In particular CentOS or Fedora if someone is using them.

I do have a RHEL 7.1 system with the udl driver and I get partial support for my USB video adapter. Sometimes it’s not detected, sometimes it is but the picture quality is very bad. I’ve had better experience with older Linux boxes (where we had a custom Xorg fbdev driver).

What’s your experience with this lately ? What’s needed ?

Thanks,
Alex


#2

Hi Alexander,

Thanks for posting. I’d be happy to answer your question.

In terms of using an adapter based on DisplayLink technology like ours are (you don’t mention which Plugable product you are using) to add an additional display, the adapters that are USB 2.0 based are fairly well supported, but adapters based on USB 3.0 are not. David Airlie of Red Hat has done some work in this area but as DisplayLink has not released the necessary bits to write a driver, he is having to reverse engineer:

http://airlied.livejournal.com/80307…

http://airlied.livejournal.com/80516…

http://airlied.livejournal.com/80797…

David is also the author of the UDL driver you mention, but in some instances customers have had better success using the older udlfb driver you mention. We wrote up a post on switching from the UDL to the FB driver back in 2012 here:

http://plugable.com/2012/06/21/displa…

Let us know if you have any other questions.

Thank you,

Bob
Plugable Technologies
www.plugable.com/support


#3

Hi Bob,
thanks for your reply and the links above. It turned out the bad picture experience was due to a faulty monitor cable and not the USB graphics. I’ve fixed it and all seems to work great.

After several retries (to make sure everything works out of the box) it looks like I don’t need any additional tweaking or configuration. The USB video card was detected, driver loaded and external monitor recognized. I was able to play YouTube video as well as presenting with OpenOffice on the USB display.

I’ve been using UGA-165 device.


#4

Hi Alexander,

Thanks for getting back so quickly. I’m glad the adapter is working properly and the issue was just a faulty cable.

Usually USB 2.0 adapters (like your UGA-165) ‘just work’, with Red Hat and Fedora having the best out of the box support due to the efforts of the aforementioned David Airlie, and I am glad that is the case here.

Thank you,

Bob


#5