DP++ ports allow for different signals (HDMI, VGA) to be passed thru the DisplayPort connector. A DP++ dongle offers the necessary pinnage for this to happen, very common are DP to HDMI adapters. By detecting capabilities of the dongles themselves, it will be possible to drive 4k displays or high frequency panels over this connection if the dongle so allows.

On Wed, Jul 27, 2016 at 11:18 PM, <Valdis.Kletnieks@vt.edu> wrote:
On Mon, 25 Jul 2016 02:07:58 -0300, Rafael Westenberger said:

> Please add this commit to wiki:
>
> Support for DP++ dongle detection

There's *plenty* of stuff added every kernel release - adding every single
new feature and device supported would make the "new feature" list unwieldy.

In 2-3 sentences, explain what a DP++ dongle is, and why detecting one is
of general interest worth mentioning in an overview....