Linux 4.6 Will Finally Bring GPU Switching For Pre-Retina MacBook Pros

Written by Michael Larabel in Linux Kernel on 12 February 2016 at 09:02 AM EST. 5 Comments
Support for GPU switching on pre-retina Apple MacBook Pro laptops manufactured from 2008 through 2013 will finally be supported by the mainline Linux 4.6 kernel.

Daniel Vetter of Intel sent in a round of DRM-misc updates today for DRM-Next, which in turn is being queued up for Linux 4.6. Normally the drm-misc changes aren't too interesting, but this time things are different: there is the long-in-development VGA Switcheroo support for Apple GMUX.

This VGA Switcheroo for Apple GMUX support was finished up by developer Lukas Wunner. As he explained in one of his earlier patch series about the changes:
The main obstacle on these machines is that the panel mode in VBIOS is bogus. Fortunately gmux can switch DDC independently from the display, thereby allowing the inactive GPU to probe the panel's EDID.

In short, vga_switcheroo and apple-gmux are amended with hooks to switch DDC, DRM core is amended with a drm_get_edid_switcheroo() helper, and relevant drivers are amended to call that for LVDS outputs.

The retina MacBook Pro (2012 - present) uses eDP and cannot switch AUX independently from the main link. The main obstacle there is link training, I'm currently working on this, it will be addressed in a future patch set.
Related News
About The Author
Michael Larabel

Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

Popular News This Week