To check whether you can use a passive adapter, is to see if the DisplayPort, or Mini DisplayPort source has the DP++ symbol above it. There are two types of conversion adapters that can be used, the first is an active adapter, and the second is a passive adapter type.

DisplayPort is quite similar to HDMI, in that it is a digital interface that is used to transfer high-definitiontop audio and video from one device to another.but dual-mode DP sources (known as DP++) can speak both DP and HDMI languages, allowing for passive adapters in the DP++ to HDMI direction. Display port is often incorporated into USB 3 proprietary connections with adapters; so you could get a usb3 to display port doc.

This is how (mainly) TVs are able to access HD sound and visuals and is done through the use of just one simple HDMI cable. You can convert DVI-I and DVI-A to VGA with just a simple adapter, and the other way around, but you to convert the DVI-D (that is to say, actual DVI) to VGA, you need active device. So is “DP is HDMI plus some extra information, so it’s easy to strip but hard to generate that info”.Higher quality HDMI to DisplayPort devices should last longer, as the connections within the wires will not degrade as quickly, so you may get much more use out of them. If the source supports dual-mode DisplayPort (also known as DP++), then you can use a passive adapter because the source can perform the conversion. It is not uncommon at all for newer technology to be backwards compatible with older technology to aid in adoption.

The idea was good, and while things initially got a little bit messy, eventually, HDMI made its way onto billions of devices, and it's still widely used today. When you convert video from a source that uses DisplayPort or Mini DisplayPort to DVI or HDMI (ex: A computer to a monitor). The Alogic HDMI to DisplayPort Converter Adapter with USB Power sends video signals from an existing desktop computer or another source device with a HDMI video output port to a projector or monitor with a DisplayPort input. By contrast, passive DisplayPort-to-HDMI converters work pretty much flawlessly, given how the signal is the same as a native signal.So if you’re looking for a DisplayPort to HDMI converter to make use of an HDMI display, you’ll need to be aware that HDMI has these limits, even if they’re unlikely to be met in most cases. Our DisplayPort to HDMI adaptors are the perfect solution for adapting your DisplayPort computer or graphics card to use a HDMI monitor/device/TV. The symbol is a D with a P inside, with two + signs to the left, one on top of the other ( Figure 4). Simply connect the DisplayPort end of the connector to your computer and plug your existing HDMI cable from the display into the adaptor. This answer and the Dell page it links to seem to imply that it's just not possible to go HDMI -> DP, without a very expensive converter box (not just an adaptor).