DisplayLink Graphics, Ethernet, and Audio Limitations on OS X 10.8.4

Plugable uses DisplayLink chips in all our USB 3.0 universal docking stations and graphics devices. DisplayLink’s chip and drivers can provide an extra display or two, along with audio and networking ports, all via one USB cable. For users seeking an affordable way to expand their Mac, this can both simplify connecting everything and increase the number of devices you are able to use – especially for thin and light Macs and MacBooks with few expansion ports.

Unfortunately, at the moment there are significant limitations, especially for USB 3.0, that will require fixes from both Apple and DisplayLink to solve. We list these limitations and known workarounds below.

Click the categories listed to the right to skip ahead for the status of open issues on OS X 10.8.4, however please note that older OS X versions may have different and unique issues as described below.

OS X Versions

Because of important Apple fixes in 10.8.3 that solve login screen problems and others, applying all available OS X updates prior to installation is recommended. OS X versions 10.8.1 and 10.8.2 are not supported, and must be updated before driver installation.

The latest updates for of 10.6 Snow Leopard and 10.7 Lion are also required for installation.

Older OS X versions such as 10.5 Leopard and 10.4 Tiger have a totally different beta-quality driver which is no longer supported: as a result, we do not recommend our USB display adapters for Macs running these OS X versions.

Audio

UPDATE: As of OS X 10.8.5, audio is working well over both USB 3.0 and USB 2.0 connections.

As of 10.8.4, OS X does not support USB 3.0 audio, so connecting via USB 2.0 instead of USB 3.0 is the only way to use the audio features on devices like the Plugable UD-3000 docking station or USB3-HDMI-DVI graphics adapter.

This issue is due to Apple not yet having a USB 3.0 audio class driver in OS X. However, we have reason to believe OS X update 10.8.5 may add this support. Resolution of this issue is dependent on future Apple OS X updates, so we cannot estimate a timeframe to resolve this issue.

If audio is important, our UD-160-A Universal Docking Station avoids this issue, since it is USB 2.0 only.

Ethernet

For our USB 3.0 DisplayLink based products with Ethernet, like our Plugable UD-3000 docking station, there are special USB Ethernet issues on OS X. To date, we are aware of two issues:

  1. IPv6 related kernel panics on OS X 10.8.4 (workaround available below).
  2. Network disconnects on OS X 10.8.x (ethernet detected as unplugged even when connected, or no network access when a valid IP is reported).

To date, all cases of IPv6 related kernel panics have been resolved by disabling IPv6 support only for the UD-3000’s ethernet port using the following command at a terminal window:

networksetup -setv6off "Plugable UD-3000"

For the command to complete, an administrative users password must be entered.

If you are experiencing issues where your UD-3000’s ethernet network connection is plugged in, however the connection is listed as cable unplugged in Network Preferences, please submit the output from the DisplayLink support tool, available here:

DisplayLink Support Tool

Video

For basic use scenarios like working with documents, web browsing, managing media libraries, or even streaming video, most users shouldn’t see any issues – however it is important to note some expected limitations of USB graphics devices. On OS X, any displays that aren’t “traditionally” attached via DisplayPort or Thunderbolt, users should be aware that a systems GPU will NOT be available to the USB attached displays. Since USB attached displays are reliant on CPU power alone, any additional load on the system (running additional programs, etc) may reduce video performance.

For a real world example, it is entirely reasonable to expect that a system would have enough CPU power to drive a USB attached display, and to update it quickly enough to reveal no issues when simply streaming video from YouTube or Netflix. If the same system is also running other CPU intensive processes (things like video editing, working with large 3d CAD files, or gaming) the performance on the USB attached display might drop- even when the “traditionally” attached displays are running well thanks to their access to the system’s GPU. This is why we recommend USB graphics only for “productivity” and “light video” usage on secondary (not primary) monitors. For a list of specific known issues and available workarounds, read on.

Some other specific issues arising from this limitation are:

  1. Disabling hardware acceleration in both Firefox and Chrome is sometimes necessary to avoid issues with mouse cursor lag or with items being rendered in odd shapes/sizes onscreen. For instructions on disabling hardware acceleration, go here.
  2. Using a USB attached display as the primary is neither supported or recommended – although users can avoid most issues with this scenario by using Spotlight to launch applications instead of Launchpad.  For further details click here.
  3. “Coherence mode” in Parallels 8 will not work when a DisplayLink adapter is in use, although it does after unplugging the adapter.
  4. Full screen video does not work in Adobe CS6 applications when USB displays are attached. Removing the USB display devices will allow this feature to work.
  5. Safari’s frequently visited sites new tab screen may flicker on USB attached displays.  Using Chrome or Firefox with GPU acceleration disabled is a recommended workaround.
  6. CoverFlow view in finder may flicker on USB attached displays.
  7. HDCP is not supported. While Netflix works in a Chrome browser window- so trying other applications may help in case of HDCP related playback issues- applications like iTunes that require HDCP will fail on USB attached displays..


Disabling Hardware Acceleration in web browsers on OS X
Because USB attached displays cannot benefit from the system GPU hardware for graphics acceleration, disabling these features in web browsers used on USB attached displays will actually improve performance. We’ve seen noticeable differences doing this in both Chrome and Firefox. Safari does not have global options to disable hardware acceleration, so using other browsers on USB attached displays is recommended.

To disable hardware acceleration in Chrome:

  1. Open Chrome preferences by using the keyboard combination “Command” (AKA Windows) key + , (comma).  Alternatively, from the menu bar for chrome, select preferences, as pictured here:chrome preferences
  2. Next, scroll to the very bottom of the preferences page.  Find and select “show advanced settings” as shown to the right.  More options will be revealed:chrome advanced settings
  3. Scroll to the bottom of the newly revealed settings, and uncheck the box pictured below to disable hardware acceleration:Chrome HWA
  4. Last but not least, restart chrome to apply the changes (close and re-open the application, or click the pictured option to “restart” Chrome.chrome restart

To disable hardware acceleration in FireFox:

  1. Use the keyboard combination “Command” or “Windows” key and , (comma) to launch FireFox preferences. Alternatively, select preferences from the FireFox menu bar as shown here:firefox preferences
  2. Click the gear icon to access the “Advanced Settings” for Firefox, then make sure the hardware acceleration option is de-selected as shown below:disable HWA firefox


Using an external display as primary on OS X
The only recommended method for using an external display as primary on OS X (using an external monitor for your menu bar, dock, and core OS X features like Launchpad) is to use a display output built in to your Mac or MacBook.  Setting a USB attached display as primary is neither supported nor recommended.

This is because LaunchPad may have substantial delays when used on a USB attached display set as the primary display. For MacBook owners, this means that whatever display you want to use to launch programs in LaunchPad MUST be attached using one of the DisplayPort or Thunderbolt outputs on your Mac for normal operation.  

While it is possible to use several external displays on OS X (as this user photo shows, there are several limits on the USB attached displays that are not present on the “traditionally” attached displays)- keep this in mind when designing your workspace. 


Have questions, or an issue that you don’t see listed here?  Please let us know – email support@plugable.com anytime, and we welcome your comments below. Thanks!

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