5 ms·

This issue was the genesis of the short-lived VirtualLink effort: https://en.wikipedia.org/wiki/VirtualLink https://en.wikipedia.org/wiki/VirtualLink VR headse

by nrp 7y ago

This issue was the genesis of the short-lived VirtualLink effort: https://en.wikipedia.org/wiki/VirtualLink https://en.wikipedia.org/wiki/VirtualLink VR headsets wanted four lanes of DisplayPort, USB 3.1 for data, and power over a single connector, and no existing standard supported that.

snops 7y ago
Interesting how you say short lived, I had a look and it's on founders edition NVidia RTX2000 series cards, though not mandatory [1] and Valve recently cancelled support for it on the Index headset. [2] Do you think it will be cancelled on the next series of cards? The need for yet another specialised variant of USB-C cables does look a downside for me, vs DisplayPort getting fast enough to need only two lanes for VR, so standard cables can be used. [1] https://uploadvr.com/nvidia-rtx-super-virtuallink/ https://uploadvr.com/nvidia-rtx-super-virtuallink/ [2] https://www.roadtovr.com/valve-index-virtuallink-adapter-canceled/ https://www.roadtovr.com/valve-index-virtuallink-adapter-can...
flafla2 7y ago
> Unlike most alt-mode; this will also remap A7, A6, B6, B7 to carry USB 3.0 signal, instead of the usual passive USB 2.0 signal. This means that one will not be able to extend the cable using a standard USB-C 3.0 cable, which has these pins mapped only for unshielded USB 2.0 signals. Also this will require the VirtualLink port to also detect the correct orientation of the USB-C plug to ensure that the USB 3.0 TX and RX lanes are correctly connected. A fun/interesting hack! But breaking superposition is a huge dealbreaker. Imagine seeing notices in software saying to flip your cable upside down...
- whoopdedo 7y ago
  Why couldn't the connections be swappable electronically inside the connector? The way that modern Ethernet ports adapt to the correct Rx/Tx without needing a crossover cable.
cesarb 7y ago
I personally believe VirtualLink is dead. Its use case (four-lane DisplayPort and USB 3.x at the same time) is also met by USB4, which I believe will be more widely implemented. However, I also believe that the VirtualLink trick of repurposing the USB 2.0 pins will end up being used by a future USB standard for two more lanes of USB4, gaining 50% more speed without reducing even more the maximum cable length.

by nrp 7y ago

snops 7y ago

Interesting how you say short lived, I had a look and it's on founders edition NVidia RTX2000 series cards, though not mandatory [1] and Valve recently cancelled support for it on the Index headset. [2] Do you think it will be cancelled on the next series of cards? The need for yet another specialised variant of USB-C cables does look a downside for me, vs DisplayPort getting fast enough to need only two lanes for VR, so standard cables can be used. [1] https://uploadvr.com/nvidia-rtx-super-virtuallink/ https://uploadvr.com/nvidia-rtx-super-virtuallink/ [2] https://www.roadtovr.com/valve-index-virtuallink-adapter-canceled/ https://www.roadtovr.com/valve-index-virtuallink-adapter-can...

flafla2 7y ago

> Unlike most alt-mode; this will also remap A7, A6, B6, B7 to carry USB 3.0 signal, instead of the usual passive USB 2.0 signal. This means that one will not be able to extend the cable using a standard USB-C 3.0 cable, which has these pins mapped only for unshielded USB 2.0 signals. Also this will require the VirtualLink port to also detect the correct orientation of the USB-C plug to ensure that the USB 3.0 TX and RX lanes are correctly connected. A fun/interesting hack! But breaking superposition is a huge dealbreaker. Imagine seeing notices in software saying to flip your cable upside down...

whoopdedo 7y ago
Why couldn't the connections be swappable electronically inside the connector? The way that modern Ethernet ports adapt to the correct Rx/Tx without needing a crossover cable.

cesarb 7y ago

I personally believe VirtualLink is dead. Its use case (four-lane DisplayPort and USB 3.x at the same time) is also met by USB4, which I believe will be more widely implemented. However, I also believe that the VirtualLink trick of repurposing the USB 2.0 pins will end up being used by a future USB standard for two more lanes of USB4, gaining 50% more speed without reducing even more the maximum cable length.