On 24 March 2018 at 19:07, Russell <[email protected]> wrote: > On March 24, 2018 9:53:59 AM EDT, Russell Reiter <[email protected]> > wrote: > >On 24 March 2018 at 08:08, Giles Orr via talk <[email protected]> wrote: > >> On 23 March 2018 at 20:01, Scott Sullivan via talk <[email protected]> > >wrote: > >>> > >>> On 2018-03-23 12:50 PM, 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-fh > d-60hz-5ms-gtg-ips-lcd-monitor-mb16ac-dark-grey/10737845.aspx > >>>> > ><https://www.bestbuy.ca/en-ca/product/asus-zenscreen-15-6-f > hd-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? > >>> > >>> > >>> The Spec you linked say it's DisplayLink, which is the software > >based > >>> video solution that requires a driver. > >>> > >>> https://en.wikipedia.org/wiki/DisplayLink > >>> > >>> USB-C is only a specification for a cable and connector, and > >somewhat > >>> agnostic about the data communications spec used across it. The > >cables are > >>> of high enough quality that they can support multiple data > >communications > >>> specs, generally referred to as alt-modes. > >>> > >>> > >https://en.wikipedia.org/wiki/USB-C#Alternate_Mode_partner_specifications > >>> > >>> Thunderbolt 3 for example co-oped the USB-C cable spec for it's > >cables, > >>> much like in the previous generations it co-oped the > >mini-displayport cable > >>> spec. > >>> > >>> Intel makes a point that a port carrying Thunderbolt 3 should also > >be > >>> cross wired with USB 3.X and Display Port hardware to output those > >signals > >>> as well. > >>> > >>> So if you want a monitor that uses a Type-C connector, your looking > >for a > >>> display-port monitor. Which your not likely to find in the portable > >market > >>> yet. > >>> > >> > >> Now that I knew what to look for, re-examination of the text and > >pictures > >> shows a couple interesting things: "USB Type-C connectivity with > >hybrid > >> signal solution for Type-C and Type-A source compatibility (requires > >a > >> DisplayLink driver for Type-A connection)." So it's implying that it > >> doesn't need a driver for Type-C. And looking at the pictures, > >there's a > >> "DisplayPort" icon next to one of the buttons on the front. So ... > >> > >> My other questions stand: > >> > >> - how can I figure out what USB protocol (3.0 or 3.1) the type-C > >connector > >> on my Linux computer supports? > > > >lspci -d ::0c03 -k will display the vendors controller and kernel > >driver in use. > > > >> - (clearer understanding leads to a clearer question here, although > >I'm > >> still not sure I'm saying it right) does Linux support DisplayPort > >video > >> over USB-C? > > Oops. No usb-c display context for this monitor. This test used the > display link binary and a USB 2 adapter on Ubuntu LTS. > > https://www.phoronix.com/scan.php?page=article&item=asus-mb1 > 6ac-zenscreen&num=2 > > > > >I think the short answer is yes. If you can hard wire a DisplayPort to > >HDMI adapter > >cable you must surely be able to sink to the host connections logically > >as well. > > > >Has somebody done this yet, I don't know. > > > >Since kernel 4.12 there has been development on a state machine for > >hosting sinks. > > > >https://www.phoronix.com/scan.php?page=news_item&px=USB-Typ > e-C-Promotion-Linux-4.15 > > > >Power management and signalling are all represented, soft-jacking is > >another issue. > > > >https://superuser.com/questions/1192638/whats-up-with-hdmi- > and-displayport-over-usb-c > > > >*Alternate mode data* > > > >https://github.com/torvalds/linux/blob/master/drivers/usb/typec/tcpm.c > > > >HTH >
Thanks Russell, Lennart. I grabbed Fedora's very latest kernel this morning (4.15.12-301.fc27.x86_64) given Russell's point that there's been a lot of new feautures related to this. After a reboot I ran 'lspci' - I have USB3.0, not 3.1. This is backed up by the Zenbook manual. The manual calls the port "USB Type-C/DisplayPort combo port" and says "Use a USB Type-C adapter to connect your Notebook PC to an external display." I didn't find anything more specific than that, but it's promising. It'll probably be a long time before I test it though! I haven't got my head around the spec enough to know: does the fact that it's USB-C guarantee that it can deliver 20v and lots'o-watts to accessories? What about accepting that voltage from a charger? I'd bet that Asus hasn't bothered to set up that port to allow charging through it as the computer also has a dedicated old-style charger/plug combo. -- Giles https://www.gilesorr.com/ [email protected]
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