2 Replies Latest reply on Jun 1, 2015 2:05 PM by wavetyler

    15.3 Drivers - MST Hub


      I'm have a brand new install of Ubuntu 14.04 running with one (1) dell U2415b MST hub monitor and two (2) other Dell 24s.   If I install Omega, (14.12) the MST hub is detected on the monitor everything is fine and I get three monitors.  However, if I let apt update FGLRX to the latest 15.3 driver, the MST hub no longer functions (is not detected) and only two (2) monitors are available no matter what I do.  The only way to get it back is to revert to the 14.12 Omega. What is changed in the latest driver that would cause this? Would not support for something like MST hubs be crucial in the latest drivers?  Am I missing something here? I've asked this question before for Ubuntu 15.04, because it suffers from the same issue (same driver version) but I get no response from anyone.  Can someone from AMD address this please?

        • Re: 15.3 Drivers - MST Hub

          Seeing as you only seem to have a single "true" DaisyChain monitor (the Dell U2415b) you technically should only be able to connect a maximum of 2 monitors. Except for the "last" monitor on this connection, both the other monitors need to also support MST 1.2 tech. As such you would need to have 2x Dell U2415b MST monitors in order to properly get 3 screens working. I realize that you can get them all working when using 14.12 Omega, but that is not a fully supported format and would not work on a stable basis and thus cannot be supported across the board.


          You can find more information about the rules for connecting multiple displays using the built in MST connectors in the User Manual for your monitor at:



          Here is a screenshot of the User Manual for the monitor you are using (U2415b) from page 11 with the rules for getting mu

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            • Re: 15.3 Drivers - MST Hub

              Thank you tekkiaussie for your response.  I understand that configuration, however, (and I should have stated this in my original question) The AMD card I use (Radeon HD 7440) has a DVI port, and a Displayport.  So, the U2415b is daisy chaining only 1 of those other monitors and the 3rd one is using DVI.  In Omega, the Displayport is recognized properly and daisy chains to the second DP monitor along with the DVI monitor giving me 3.  In 15.04 (or 14.04 with driver version 15.3) Only the U2415b and the DVI monitor are detected.  I do not believe this breaks the supported methods as you described.