[GTALUG] USB-C/3.1 Video and Linux

[Russell]

On March 29, 2018 11:35:07 AM EDT, Lennart Sorensen via talk <talk at gtalug.org> wrote:
>On Thu, Mar 29, 2018 at 11:17:58AM -0400, Giles Orr via talk wrote:
>> 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.
>
>Well remember that to make things confusing, USB 3.0 was renamed to 3.1
>Gen 1 by the USB 3.1 standard.
>
>So USB 3 now has:
>3.1 Gen 1: 5Gbps (Was 3.0)
>3.1 Gen 2: 10Gbps
>
>USB ports do not need to support the USB 3 PD (power delivery) spec.
>It is optional.
>
>USB 3 really has made USB very complicated (although also more useful).
>

The spec for USB 3.2 was released last fall. This is what it looks like to me, so far. 

USB 3.2 "SuperSpeed+" is what will now provide double the bandwidth (2 gigabytes) over the existing USB-10gib/ 3.0, (1 gigabyte) bus. It does this by taking advantage of USB Type C connectors and vendors own (flip flop) logic. 

Logical states for a Type C cable are flipped, unflipped, twisted and untwisted. Endpoints may be ack'd either as a remote sink by their own servient demand for voltage or; in the case of "SuperSpeed+",  the USB power lanes are co-opted for double the data rates. 

I suppose 3.2 logic will take care of all the possible signal switches, so you don't accidentaly send 100w to something asking for 15w. 

Since the specification allows for the data stream to contain timing bits, video and audio sink MUX is managable. As for Type-c  DisplayPort video. The notes on Type-C connections & 3.2 host/sink protocols indicate that there is a fair bit of restrictive IoT type hardening going on; restricting firmware update requests etc. There is no reason not to use all that bandwith an connectivity for multi-media so its probably more a matter of when then if.

So when it is decided on a single logo for an "omnibus" connectivity device and protocol stack, consumers will be able to say I can buy this because I can stream a movie to my device while charging it at the same time.

Not my biggest priority, but people love the convienience. Where Linux distros may lack certain convieniences, they are replete with opportunities to do things in non standard ways that other OS's dont have.

I think I just read that Windows 10 now has a virtual linux console. In 2000 I ran Win98 in  Win4lin terminal albeit sans DirectX on a 300mhz Celeron OC'd to 500mhz. That was fun but pointless. I deleted Windows to make more room for Linux. It's more fun.


>-- 
>Len Sorensen
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-- 
Russell