[GTALUG] USB-C/3.1 Video and Linux

[Lennart Sorensen]

On Fri, Mar 23, 2018 at 12:50:50PM -0400, Giles Orr via talk wrote:
> A couple days ago I got a Best Buy flyer, and they have this item:
> 
> https://www.bestbuy.ca/en-ca/product/asus-zenscreen-15-6-
> fhd-60hz-5ms-gtg-ips-lcd-monitor-mb16ac-dark-grey/10737845.aspx?
> 
> It's a portable IPS LCD screen from Asus.  I have a similar item from about
> three years ago that has two connectors, one for USB power-only and the
> other for VGA/HDMI.  There were other models at the time that used only one
> connector, USB for both data and power - but that required a driver (and
> would have been painfully slow if it was USB2).
> 
> But now here's this new model: it's one connector only, USB-C.  And
> presumably USB3.1.  And USB3.1 can carry video.  But at this point I get
> lost among the standards and their implementations and which one supports
> what.  I have an Asus Zenbook (it's Linux-only at this point) that has a
> USB-C connector, but I suspect it's USB3.0.  So the first question is: how
> do I check that?  Second, does Linux support video-over-USB3.1?  Do I need
> a special cable?  Is this "Thunderbolt?"  How can I check if my machine
> would support this?
> 
> I admit that I'm probably not going to run out and buy this tomorrow as the
> old one is mostly sufficient for my needs, but I'm very curious about the
> state of Linux support for USB3.1 and Thunderbolt's many features.  And I'd
> like to know if my USB-C port supports USB3.1.

The manual says it uses DisplayPort Alt Mode for USB Type-C.  So if you
connect it to a system that supports that mode on a USB type-C connector,
it should just work as a DisplayPort screen.  If your system does not
support that, you can use any USB 3 port but you need a driver in that
case to run it as a USB video adapter instead.

Linux as of 4.6 kernel appears to support DisplayPort over USB Type-C
at least on some systems.

-- 
Len Sorensen