Explaining 4K 60Hz Video Through USB-C Hub (2019) | Hacker News Reader

Explaining 4K 60Hz Video Through USB-C Hub (2019)

bigmessowires.com

158 pointsWayToDoor108 comments

I struggled for a long time to find a "full featured" dock that could support my setup with a single cable. I wanted 3x 2560x1440@60 monitors, wired ethernet, USB 3.x, and power without having 5+ cables to move around.

Last year Dell finally released the WD19TB and it's awesome. https://www.delltechnologies.com/resources/en-us/asset/data-...

I happen to run an XPS with Arch & KDE Plasma and everything worked perfectly out of the box. Highly recommended for anyone who has a TB3 laptop and is looking for a good dock.

The problem with TB used to be the power consumption of the PHY chip.

A guy in a coworking next to me has a Dell dock which makes his fans spin, and the laptop body painfully hot to touch.

How is it for you?

Mine stays warmish but not enough to make the fans consistently spin. The heat generated by using the dock is no different than what's generated by using an AC adapter with individual DP & USB cables.

This typical for laptops with discrete GPUs. Outputting video over TB can often only be done by the discrete GPU. I do not know the reason why this works this way.

On my Lenovo X1E, this is also the case. Thunderbolt video output only works via the nVidia GPU (instead of the Intel graphics on the CPU). So connecting the TB dock causes my fans to spin up, as the laptop is now rendering my desktop using a power hungry nVidia chip.

This is still noticeable in lower power devices.

I have discovered that if I leave a usb cable plugged into a MacBook Air M1 usbc socket in standby, it draws about half a watt extra, even though the cable power draw is zero.

This means the battery goes flat in a few days vs a few weeks in standby - the PHY seems to be using more power in standby than rest of laptop

Thanks for the recommendation, I've been seriously considering one of these for my XPS.

As a side note I am deeply in love with my XPS 9310 (Tigerlake) on Kubuntu (kernel 4.11). Battery life is INSANE, instant wake and sleep, keeps cool, but still has thermal overhead/power (thanks to the fans) to do large kernel compiles or other serious hard work. Also the screen (I got the non-4K model) is very pretty, sometimes I just look at it and go 'wow, that looks good'. Excuse me if I gush too much.

The recent XPS lineup has been really great especially with the mainline kernel.

I have a 15" so the thermal issues were a bit of a challenge at first. I ended up undervolting the CPU and now I get decent battery life (~4 hours) and no thermal issues.

As for the dock- it has absolutely been worth every penny.

Can you boot off a USB-C external drive plugged into the hub?

I have an XPS, a Sitecom USB-C hub, and a Samsung T5 drive. Booted off its internal drive, the laptop can see the drive through the hub. But it can't boot off it. I don't know why; i imagine that a USB-C hub is not transparent, and the host needs to explicitly reach through it, but the XPS firmware doesn't know how.

Yes, I can. Note however, that this is not a USB dock- it's Thunderbolt.

In my particular case (literally just tested this) I needed to enable Thunderbolt boot support and change the security level (I have my thunderbolt settings pretty locked down).

Booting off both a USB drive and a TB drive worked.

Thank you! I am hazy about the relationship between USB-C and Thunderbolt, but this information motivates me to go and find out!

I made an account just to share _my_ experiences with a Dell XPS 9300, Dell WD19TB and one Dell U2719x Display, running the latest Linux Mint, in Cinnamon flavor. There's a reason, I'm spelling out Dell so many times here, because my expectations were that such an all-company-x setup would work out of the box with the least amount of problems. Sadly it did not. Currently the setup is workable, but what I've experienced in the half year I'm running it was nightmarish. The thing wouldn't power up, screen would black out and not come on again during meetings, display must stay on all the time (no power safe), sleep is impossible because the system won't come up again or go to sleep again after a few seconds of waking it up. Web research has lead me to believe, that I'm not the exception, but rather the rule and there might be a reason Dell is still sending out firmware updates for the XPS and the dock (which in general is greatly appreciated). I have to add, the Laptop sits closed in a stand behind the screen, which might contribute to my problems, but I just couldn't let this 100% recommendation stand here without an opposite experience ... I hope this it's working out better for everyone else, but this is my "story". Dell support is no great help either and a time investment I am not happy to make anymore after several tries.

Thank you for pointing this out- as individual stories our experiences are anecdotal but combined they paint a different picture. I was hesitant at first when I ordered mine and expected to have problems as others did.

I should also point out that I use an XPS 9570.

I am happy for you, having a positive experience -- and partly because of that, slightly optimistic that Dell might improve my and my peers' situation.

And of course you are right: A single anecdote is just that, but a few more may paint a rather well-rounded picture.

Cheers

To build on what someone else had said- firmware updates may play a roll here. While I do think any manufacturer should test things before they ship I am grateful that Dell does seem to keep pushing updates for them.

I did install the latest firmware when I bought mine (early 2020) and was able to through Linux. I also had a few BIOS updates I had applied before I even bought the dock and do recall a few of the change log entries mentioning TB dock fixes. Perhaps the same will be true for your machine.

>To build on what someone else had said- firmware updates may play a roll here.

Yes, I am checking those.

Also with you on the firmware development process. Just wished I hadn't been such an early adopter ...

I've had similar issues with my Lenovo second gen (AN40) thunderbolt 3 dock, which are mostly fixed with firmware updates.

The thing is: TB docks are _very_ complicated devices, consisting of multiple subsystems each running their own firmware. With the Lenovo dock (and I assume the Dell's are not much different) there have been numerous firmware updates over the past years. Updating them usually requires a windows application, the Linux fwupd can only do some (but not all!) firmware updates for the dock.

Anyway, what I am trying to explain here is that you should check if you have updated all parts of the dock's firmware. I recommend to use the Windows tools for that, don't trust fwupd to be able to update all parts of the dock.

I also suffered from the screen randomly going black, but that turned out to be a firmware issue with my display (LG 43" 4k). As it turns out: firmware on a display can also be updated. I needed to connect my laptop through a USB-C cable to the monitor, then run an update tool from LG. The update tool was of course windows only, and even buggier than the Lenovo dock firmware updater, but it did work! No more screen blackouts.

I am regularly checking for updates using fwupdmgr. Did a few updates and things improved a bit. Did not try and firmware-update the display yet ... because I didn't know that was a thing. Thanks for the hint, will check that.

EDIT: I'll also check for a Windows tool, to see if it offers more updates.

Have you tried another operating system? I have used Cinnamon on an XPS 9360 with an external display hooked up via thunderbolt to displayport adapter. I had some of the issues you described, especially the sleep issues.

I asked about this because I'm not sure your issue is totally related to using a thunderbolt dock. Laptops generally require a lot of OEM developed drivers to fully function. It is very possible you would not experience these issues with Ubuntu which is fully supported by Dell on the XPS.

My understanding is that Mint is heavily based upon Ubuntu and assumed there might be none such differences. Thanks for the suggestion -- I will definitely investigate in that direction.

Have you tried the official DE edition Ubuntu distro to see if any of your issues are fixed? My experience is it's pretty good, one of the better linux laptop experiences you can get on a machine with comparable industrial design. Now, perhaps tellingly, I still use Windows 10 on my own 9300. While I appreciate Dell's efforts, I have yet to work with a linux distro on any laptop that does "laptop" things well, like docking/undocking seamlessly, autodetecting docks and USB hubs, having sensible power management settings, etc. So I just run windows now and get my linux fix with WSL.

With my 9300 I use the dell U2720Q monitor (27" 4K with built-in USB C hub). It does 4K@60Hz along with USB 3.1 data over the single USB C, non-thunderbolt cable provided (via HBR3/DP1.4 as mentioned elsewhere) in the box and basically everything worked perfectly immediately and I've had zero issues. Dell/Windows is still "not fantastic" at other laptop things, or at least not as good as apple, but one of the better experiences on the windows side in my opinion.

Relevant to the OP, I would add that when I did go to get a longer cable to connect the 9300 to the monitor, I ran into all of the insane issues described. "WTF, every cable looks identical but support wildly different features???" You have to become an mini-expert in USB technology to know what the hell you're looking for, no idea how non-technical people can even do it.

I haven't really given Standard Ubuntu a chance yet, because I don't like the direction they're going in recent years (different topic). But will definitely consider it, if my issues persist. My XPS is a work laptop and I haven't used Windows for work in over a decade or so, which makes switching a potentially bigger undertaking ... which I might avoid, if possible.

Thanks for the cable length tip! Hadn't considered this and am using a 1,20m+ cable -- will definitely try a shorter one.

I have the WD19TB and have a lot of issues with it. I need to unplug/plug it multiple times a day since things stop working (display not detected, USB devices not working, ...). Both on windows and Ubuntu. I also can't seem to get 2*4k60hz working.

Also have the caldigit ts3 plus which is better but doesn't provide enough power for my dell precision 7550

TB3/USBC is insane and a mess. Whoever decided to use the same connector is insane.

I have varying cables with the same connector which do:

- Power but not data

- USB Data but no/low power

- USB Data but only at USB2 speed (why?)

- USB Data but only USB3

- TB3

- LOL don't forget USB-PD

At least in the late 90s ecosystem of a dozen different connectors you could visually identify them. Now I have various special unicorn cables around the house which look the same, but only work for use case X or Y or Z.

Examples are things like - I have one cable that can charge my camera over USB-C, and one cable that can transmit data between my camera & MacBook.. but neither does both. I suppose I could acquire a third cable to accomplish that.

This is a feature, not a bug.

The USB-IF is just a bunch of manufacturers getting together to agree on a standard. The vast majority of them are interested in one thing: lowering the BOM. Cheap, cheap, cheap! That's what matters. Making things super cheap means making lots of the spec optional so they can re-use existing chip designs, less expensive cables, etc.

If they can make things easier for customers that's a nice bonus but ultimately it doesn't matter. The free market does not always optimize for what you think it should optimize for.

Have look at the USB-C pinout, it will be obvious then. (E.g.: https://www.allaboutcircuits.com/technical-articles/introduc...)

Wrt USB2 vs USB3 - these have separate pins and wires. USB3 requires four extra wires, which must be of higher quality than those for USB2; their presence is the difference between 2 EUR and 10 EUR cable.

TB3 is quite different cable; if it is over 0.5m, it will be an active one.

I'm over IT for about 40 remote workers. One of the comments in this article rings so true about the pain of using USB-C to DisplayPort:

"I hate my USB-C monitor ports that work is making me use. Sometimes when I plug the USB-Dock in, it works fine. Other times I get one of the two 1920×1080 monitors attached to turn on. Others, no monitors turn on, and I have to unplug it and plug it back in. Then it usually works."

It's SUPER finicky and picky, pretty much across the board. I find this true for the PC/Windows- macbook pros seems to work MUCH better, even with triple-2k monitors, but still not perfectly every time.

I have a macbook and I’m sad to report it’s just as finicky

I think it depends a bit on the generation. I have a 15” MBP that inconsistently connects to the usb devices connected to the monitor. And I have a 16” 2019 one that has never failed to connect properly to the exact same setup. Of course there could be a different configuration of monitor and usb devices that my 16” would fail to work consistently with.

The problem I have with my MBP is that it randomly forgets which monitor is which, so the left one becomes the right and vice versa

It's interesting how experiences differ. For me, USB-C <-> DP has been super reliable for years - Mac, Linux, and Windows. Admittedly, that was with a USB-C <-> DP (Alt mode) cable without any other functions.

Does it work better to keep the monitors powered off, plug in the hub, then turn on the monitors?

This looks to me like the controllers are sometimes badly implemented.

I have a HP ProBook with a USB-C/DP output that I plug into an LG monitor with a USB hub. The hub works in USB2 mode + 4K@60Hz (as advertised by LG). This has worked consistently for me for more than two years, using Arch Linux + X11. Sleep, plug, unplug whenever I like, it just works. It seems to also work fairly consistently when colleagues plug in their Windows laptops (also HP).

I also have a HP EliteDesk with a Thunderbolt + USB-C / DP port. This is a shitshow. The same LG monitor works every time for BIOS and such when connected through USB-C.

Installing Windows works. The Windows logon screen sometimes shows up, but not reliably. The Windows desktop has only ever worked once. This same setup usually works with Linux/X11. But after a display sleep, it sometimes figures it can only do 4K@30Hz. Sometimes it chooses some other random resolution. If I unplug it a number of times, it may end up working again. Maybe. Or maybe not. Sometimes I have to reboot. Which may or may not solve the issue.

Plugging in a thunderbolt display (Apple) works more often. But if the screen goes to sleep, there's a good chance it will wake up with some ridiculous resolution, like 1280x720. It's impossible to change it. If the computer goes to sleep or if the monitor is unplugged, it's game over. The screen will never come back again unless I do a cold boot (turn off & on, reboot won't do).

I keep hearing people complaining about macbooks being unreliable with external screens. I wonder if it isn't the same kind of issue with a broken controller implementation somewhere. I've never had the slightest issue with external screens on my 2013 MBP (15" with nvidia dGPU). Thunderbolt, 4k@60Hz, you name it, it works. Plug / unplug when it's running, when it's sleeping, whatever, it just works as expected.

A friend has a Thinkpad that if the battery is fully charged when the machine is turned on with the monitor out plugged in then the monitor works perfectly from the USB 3, if however the battery is not entirely full then the display gets no signal. It requires a reboot once the battery is completely full.

It is reliable in producing an image or not depending on battery status. I have no idea why though and neither does support, they haven't fixed it for a year at this point so I doubt they ever will.

Be sure to read the update at the end, since the article is partly outdated with DisplayPort 1.4. With DP 1.4, only two lanes are necessary thanks to HBR3 (and DSC). So, you can have 4k@60Hz while also having USB 3.1 Gen3 at 10Gbit/s.

E.g. I use a Lenovo USB-C Dock Gen 2, which supports this. You can have it all with just a single cable.

Unfortunately, Linux misconfigures the lanes (does not use HBR3) for this hub and apparently some other hubs [1], so 4K@60Hz is not supported using a single cable. Windows 10 works fine and my wife's MacBook as well.

[1] https://gitlab.freedesktop.org/drm/amd/-/issues/1317

Does this require cable/hub support? I've currently got a hub which provides USB3 ports as well as HDMI, and as expected, only goes up to 4k@30Hz.

Would a simple software change & hardware support on the host side be enough, or does the hub still need to be upgraded?

That hub presumably has a DP-to-HDMI chip that will never support DP 1.4. HDMI isn't for monitors anyway...

It's so annoying that many monitors (e.g. common LG models) have 1x DP and 2x HDMI.

I have a monitor with 1xDP and 2xHDMI and it's perfect. I use the DP for my desktop, one HDMI for my laptop dock, and the other HDMI for anything I might choose to use instead (console being the only thing I've used so far)

I have one of those LG monitors, although mine has a usb-c input which also handles display-port (so it's 2xDP + 2xHDMI).

What really bugs me with HDMI is that monitors and computers never seem to agree on the image standard and for some reason always default to washed-out colours, even when connecting a PC to a PC monitor (as opposed to a TV).

Under Linux/X11 I know how to set it in full range mode [0], but I was using such a monitor at home and connected it the HDMI output of my gaming PC (Radeon GPU) and couldn't figure out how to fix the washed-out colours. In the end I bit the bullet and bought a display-port switch.

Now windows complains about the "limited display connectivity" (the monitor has a USB hub whose upstream is the usb-c/dp connector), but at least the colours look OK.

---

[0] `xrandr --output HDMI1 --set "Broadcast RGB" "Full"` IIRC

At the very least it requires DP 1.3 support of both the dock/hub and the machine that it is hooked up to for HBR3 and DP 1.4 for DSC. If either uses an older version, it doesn't work. I don't know about HDMI, there is HDMI alt-mode, but I think many docks use DP-Alt mode for HDMI as well.

tl;dr: requires support from the host and the dock.

> there is HDMI alt-mode, but I think many docks use DP-Alt mode for HDMI as well

DP alt-mode is ubiquitous, while HDMI alt-mode support is very rare on both host and peripheral sides.

If this is the case, then how does the Caldigit TS3 Plus dock (https://www.caldigit.com/ts3-plus/) support 4K@60Hz video and USB 3.0 ports while only using DisplayPort 1.2?

It uses Thunderbolt 3, not plain USB. Although sharing the same connector, these are different protocols

That's a thunderbolt dock, which has higher bandwidth than usb 3 and it's variants (usb4 mostly merges with thunderbolt 4 but not entirely)

Thunderbolt mode over USB C is basically a direct PCIe connection along with DP.

I’ve that exact set up right now and it works great!

Kubuntu+thinkpad nano+2.0 dock+4K at 60hz

Maybe they issue only crops up on AMD APUs? Though, in the linked bug report, there is also someone who has an Intel Iris Xe GPU with the same issue.

I think the whole concept of usb c/tb3 is flawed, cables should be inside the computer not outside. I have a fairly simple setup: 2017 Macbook Pro with two TB3 ports, a Dell monitor, an external SSD, a TB2 soundcard and a wireless usb mouse, because a traditional mouse works better in VMs than a Magic Mouse. This setup worked perfectly with a 2015 13" MBP: the HDMI port supports the Dell monitor, I connected my soundcard to the dedicated TB2 port and I still had two USB3 ports for my mouse and the external ssd. Now comes the revolutionized & courageous setup with two TB3 ports: First of all I had to buy a USB3 dock. That's ok but still 50 euros down the toilet. Then an Apple issued TB2-TB3 adapter which was another 100 euros. But then I figured I can't connect these devices at once so I've had to buy an Apple Issued Digital AV Adapter for another 100 euros. We are already at 250 euros and the fun part just starts: If I connect my Dell monitor and my soundcard (even turned off) at the same time the monitor starts to flicker and the soundcard starts spitting out dirty electrostatic noise. Yes, a good old ground loop! So now I can't listen to music with my soundcard and have my monitor plugged in at the same time. I can't use my wireless mouse because the wireless dongle is too far from my USB3 dock. I can't use my external ssd reliably because every time I put my Macbook to sleep it disconnects in a way that i have to phisically reconnect it. Every fkn time. So I thought, gee I just have to shell out another 300 euros for a Caldigit TS3+ and all my problems will be solved, right? USB-C ecosystem: hold my beer The statical noise comes through the TS3+ as well plus it heats up my Macbook to a completely pathetic degree, so it throttles. Because it has to be thin too. TDP is just stat for nerds. SSD is still unreliable and the dock is still too far from my mouse to have a stable connection. In the end I spent 550 euros on completely useless environmental waste bullsh*t that shouldn't exist at all. I get what Apple and the whole industry had in mind with usb-c but it is flawed by design. It has to be reengineered from the ground up.

Hope you don't speak Spanish and can enjoy this one: https://www.youtube.com/watch?v=-I9n-cjl7zg

Aha. Now I understand why my Lenovo USB-C dock doesn't do 4K@60 on my Mac. It's not thunderbolt capable.

By the way, it does have an extra limitation on Mac. It only supports one external display. Apparently this is due to the Mac lacking support for Multi Stream Technology over DisplayPort (because it has Thunderbolt instead).

Unfortunately Thunderbolt hubs are very expensive as the article also mentions. So I added a DisplayLink adapter for my third display (one 4K@60 directly connected to a USB-C port, the hub on the other with one HDMI out and the display link and lots of other USB stuff :) )

By the way DisplayLink support is pretty good now on Mac. Even for the new chipsets. I wouldn't call it nonexistent as the article does. It does have some limitations though, like Night Light not switching on.

The M1 laptops don’t support more than 1 external display, either. Same laptop with Intel chip does, though.

"Apparently this is due to the Mac lacking support for Multi Stream Technology over DisplayPort"

AIUI it's not the Mac (hardware) that lacks this support, but the operating system (MacOS). Running Windows on the same hardware will allow you to use two monitors.

What's annoying is that the "Thunderbolt" connectors ALSO depend on the chipset internally (and how it is routed) - for example on my MacBook Pro (15-inch, 2017) - I can drive four external monitors but ONLY if I connect two on each side of the laptop. I have two daisy chained via Thunderbolt but I cannot use that second Thunderbolt port on that side for a third monitor - it must be on the other side.

At least you have USB-C on both sides. Dell is shipping 'professional' laptops with USB-C on only one side.

But does it have the problem GP is describing?

If not, I'd say it's definitely better than his/her MacBook Pro since they're at least functioning.

If I understand your issue correctly, this is a macOS issue, where macOS only support DP daisy-chain (MST "Multi-Stream Transport") for mirroring content, not multiple screens.

https://medium.com/@sebvance/everything-you-need-to-know-abo...

(I stumbled upon this limitation myself recently. Supposedly Windows doesn't have this limitation though I haven't tried it myself)

I don't know what I'm technically using, but it's two monitors daisy-chained via Thunderbolt and they're not mirrored.

System Report says "Thunderbolt 2" is how they're connected.

Part of it may also depend on the dock and how it routes the TB lanes. My dock uses 2 lanes for dock features and does passthrough for the rest. Are you able to daisy-chain your monitors off any of those ports without the dock in the path?

I have no dock at all (though technically the monitors may be a dock).

Apple Thunderbolt 3 to Thunderbolt 2 cable -> 34UM88 -> Thunderbolt 2 to Thunderbolt 2 cable -> 34UM88.

To make it even more fun, Thunderbolt 3 looks like USB-C and Thunderbolt 2 looks like Mini DisplayPort.

https://i.imgur.com/5TJaIqg.png

(Technically I do have a dock but it's on the other side and is unrelated).

To make it even more fun, Thunderbolt 3 looks like USB-C and Thunderbolt 2 looks like Mini DisplayPort.

What do you mean? Thunderbolt 3 uses USB-C connectors. And you can also use a Thunderbolt 3 cable as a USB 3.1 Gen2/DP-Alt/PD cable.

The big annoyance is that it doesn't work the other way around. There are even USB-C cables that only carry USB 2.0 and do not have the SuperSpeed lanes. So, they are not only worthless for Thunderbolt 3, but also for getting good tranfer rates using newer USB revisions. Worst of all is that there is no cable marking system.

Exactly - I have no easy way to tell if something is "USB USB-C" or "TB3 or TB4 USB-C" especially on the adapters. It's frustrating getting everything hooked up.

it's hilarious you know. for almost 20 years we had this perfect "it sits it fits" approach to usb, now here we are, four standards three cables one connector. easily avoided by just keeping a different connector for each spec...

We even had USB 3.0 type B (a connector that take two different kinds of USB type B) - but we've moved on from that. It's understandable that if you have a interface that is compatible with another (Thunderbolt 3 can run USB 3.2) that the connector is the same, but it's frustrating.

At least usually you'll get something that kinda works.

The USB-C connector isn't for USB3. It's for any version of USB. It's perfectly valid to have a 1.1 12Mbit HID using the USB-C connector.

I didn’t say that. I even mentioned cables that only carry USB < 3.

I am trying to get usbc connection to work on 4k monitor, and i tried 5 different usbc cabkes, only one worked.

Every week it falls back to 30 fps and needs to be replugged, caressed, and incantations

I use HDMI and it works great. It's hard to see USB-C as anything but a failure for devices other than smartphones/tablets.

I have two of these. They always work without any issues:

https://www.coolblue.nl/en/product/723407/startech-usb-c-to-...

Something similar happens to me often with a Dell monitor and MacBook Pro over usb-c. What I need to do is after the monitor turns on at 30Hz, turn off the monitor (don’t touch cable) and then turn back on.

I know “have you tried turning it off and on” sounds ridiculous, but it always reliably brings me back to 60Hz.

I bought a usb-c dock earlier this week. "Selore 8 in 1" (£44) with a separate usb-c power charger and an extension cable (2 meter male to female usb-c cable) it seems to work great. Out of the box on Debian Stable. I installed autorandr and saved my laptop's solo profile and the preferred arrangement when I use the dock with my monitor and it's fantastic.

I slap a single cable into my laptop when I plonk it on my desk and I get my monitor, keyboard, mouse autoconnect and my laptop starts charging too. This is the future I wanted for my home office arrangement. One cable does everything. I wish it were my office too

The device does have some interesting small print like the article says, so it was an interesting read. 1 monitor = 4k @ 60hz, 2 monitors = 4k @ 30hz (It has 2xHDMI outputs) but you can have two monitors at 4k and 60hz IF they mirror each other too. Regardless, I'm happy with 1080p (always at 60hz) so it doesn't seem to affect me.

I would recommend them even if the article does suggest they aren't quite as mature as they should be yet.

What, specifically, does this imply for the number of external displays one can attach to a raspberry pi 4 ?

Naively, you might think that with 2x USB-C ports, you could attach two of these:

Cable Matters 201055 – 2x DisplayPort, power, ethernet, 2x USB2

... and also attach something to each of the onboard HDMI port and have a total of six monitors.

However, I don't think that's the case because of something-something-video lanes/memory/bios something-something ...

Does anyone have a finer grained understanding ?

EDIT: I am reminded that this post[1] discusses an alternate route using the CM4 and the pcie port on the breakout board ... and failing to succeed in using a pci graphics card. USB3 monitors seem a more promising avenue but, again, I think there is some memory/BAR limitation ...

[1] https://www.jeffgeerling.com/blog/2020/external-gpus-and-ras...

For a Raspberry Pi 4B, the USB-C port does not support displays, only power and USB 2.0 data. The other pins are not connected to anything.

Without extra hardware, you can only connect displays to the two microHDMI ports.

There are, however, the two USB3 ports which you'd think could be used to drive displays ... I believe they cannot be, however.

Only DisplayLink... but I've tried to compile the DisplayLink drivers for Pi4 for my adapter and failed miserably.

In other words, it's a big mess.

Everything involving a USB-C cable seems to have been a big mess since day 1.

The argument for having the same connector for everything only works when you can plug in a cable and it just works.

If I need special cables and capabilities for this, that and the other let’s just go back to having different cables so it’s at least obvious when we’ve got it wrong.

I disagree strongly, although I'm sympathetic.

Yes it took far more research than ideal, but I have a TB3 dock currently charging my computer, connecting a mess of USB peripherals and connecting to my 4k monitor at 60 hz using only one single cable and port, and it's wonderful. Totally worth it.

How reliable is it? Everyone I know where I work has problems with their Thunderbolt breakout boxes.

I have an OWC Thunderbolt 3 Pro dock; I use it with my work-issued 16" MBP and 2020 MBA. I have a 1440p and a 4K screen attached; both running at 60Hz.

It was rough at first when I picked it up last year. However the driver updates in Big Sur seem to have fixed my complaints, particularly with the MBA that almost never worked.

It works pretty well now. I unplug my work laptop and swap it for my personal one when I want to work on personal projects, and things just work.

My biggest complaints about this dock now are that the fan is loud, and it only charges at 60w. I worked around the noise by attaching it to the underside of my desk, so it's pretty hard to hear now.

Not the person you are replying to, but I've been using a Belkin Thunderbolt 3 Dock Pro for the past year, and can only claim positive experiences.

No reliability issues whatsoever, despite me switching the dock between my work laptop and a personal laptop almost daily. The dock is connected to a bunch of peripherals, as well as 2 external monitors (one 1080p, another 4k@60hz). Only one cable going out of my laptop (connecting the laptop and the dock, as the cable connecting to the dock also charges the laptop at the same time).

I have the same experience with the dell usb c dock I use at work. Two 1080p external monitors, ethernet, usb hub, and I've never had a single issue with it.

Been using a CalDigit dock with two 2017 Macbook Pros (one work, one personal), basically zero problems. There was a slight hitch with the ethernet port when I first started, but it wasn't hard to fix.

Yeah, I remember being excited at the beginning thinking we finally had one cable to rule them all.

Now we're a few years in and seeing a USB-C port just fills me with dread cause I know I'm gonna have to do research. And I yearn for the days where if I'm hooking up a monitor or something, I see an HDMI port and know exactly what that port is for and what kind of cable plugs into it. Seeing a USB-C port in something could mean any number of things.

It would be interesting if the author mentioned not just about 4k60, but also how do you get something like 10bpp color. I have a MBP and can watch YouTube videos in HDR on the laptop screen, but not through the hub I have.

Relatedly, does anyone have any solution for switching a 5k LG monitor between two Macs? There seems to be only a single KVM switch that does that, and it's around $500. It also does not switch one Thunderbolt, but two Display Ports, so it seems that you would additionally need a bunch of adapters which split the USB-C Thunderbolt cable into two Display Port connections, and back together at the other end.

Note that there seem to be more solutions for 4k, but it's my understanding that those don't work for 5k.

If you aren't switching between your computers too often, you can just get a USB hub like this and switch between display inputs from your monitor: https://www.amazon.com/gp/product/B083JKDNRJ/ref=ppx_yo_dt_b...

My monitor only has a single input, that's the problem I'm trying to solve. I don't need to switch USB.

Use a DP 1.4 switch: https://www.amazon.com/Angusplay-DisplayPort-Switch-Bidirect...

I tried ConnectPro's DP 1.4 KVM and the display blacked out constantly in MacOS. Friends who purchased the same KVM ran into the same issue with displays that push DP spec to the limit like 3440x1440@144.

The switch I shared works just fine. From time to time (once every 1-2 months maybe) the display blacks out for a second but a computer restart does the trick, or reconnecting cables. Also make sure to get HBR3 displayport certified cables.

Just to confirm, this does work with LG 5k monitors? The resolution there is 5120x2880, which is significantly more (the vertical resolution alone is doubled, and then some for the horizontal), but I don't know the refresh rate, so the bandwidth could still be similar maybe.

EDIT: I'm also wondering, the only switch I know to be working uses two display port cables to the monitor (which I'd have to adapt to one Thunderbolt 3 instead), while your device only uses one. That doesn't bode well...

Not sure:

irb(main):003:0> 5120288060 > 34401440144 => true

It won't work with the LG Ultrafine 5k, which requires a Thunderbolt connection to run at full resolution, and behind-the-scenes is a tiled pair of DP1.2 displays.

It ought to work with a DisplayPort 1.4 5k, though there aren't many of those.

Thanks. So as far as I can tell, that ridiculously expensive switch is still the only option (if even, I wasn't able to fully confirm), and nowhere near worth the cost vs. just physically swapping the cable between computers.

> DisplayPort 1.4 can deliver 4K 60Hz video using only two lanes, with a new high-bit-rate mode called HBR3 with a compression mode called DSC. This makes it possible to get 4K60 video and USB 3.1 ports in the same hub, but only if the computer, hub, and monitor all support DisplayPort 1.4 and HBR3.

You don't need DSC to display 4K60 over two lanes, only to go above that or add HDR too.

Also displayport 1.4 support doesn't guarantee DSC for some reason.

If you're buying a hub now, you don't want any of these things, you want Thunderbolt 4. I'd really like to see an equivalent article for it.

It blew my mind the other day when work gave us one of Apple's hdmi/usb/charge multiport adapters, that it could power 4k60 and a USB3 port without using thunderbolt under the hood. It was my understanding its either 4k60 with no usb, or 4k30 with usb. I'm assuming its using this newfangled HBR3 under the hood, or perhaps it actually is using thunderbolt secretly.

If you're talking about the "USB-C Digital AV Multiport Adapter", the product page lists which Macbooks can do 4k60, and which can only do 1080p60/4k30. Those which can do 4k60 all support TB3, so I'm guessing it uses Thunderbolt to achieve this.

Previous discussion of this post (2019, 171 comments): https://news.ycombinator.com/item?id=21532795

It has also been mentioned in 10 other HN comment threads.

Found via https://ampie.app/url-context.

Yeah, USB C is a mess and Thunderbolt 3 is obviously the superior 1-cable technology.

Unfortunately, though, Thunderbolt 3 is a piece of sh*t, too [1]

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1766076

With the following constraints how would one manage to have the less amount of cable dangling around?

1 PC (personal use, desktop or laptop)

1 work laptop

2 Monitors

Keyboard & Mouse

Be able to connect the work laptop with only 1 cable and switch keyboard mouse and monitors to it

Maybe should I look for a KVM switch instead?

You could use a wireless mouseand keyboard that support being connected to multiple computers. I have a Logitech MX Anywhere mouse that works really well, and I know there are keyboards that do that too.

I would look into usb switcher for peripherals and dock for the laptop. Manually change displays using on screen controls.

Having video switching gets real expensive and only a few KVMs support high refresh / high resolution displays.

Is there an additional constraint to "not unplug things from your personal machine"?

If not, and you can get two machines with Thunderbolt, a TB dock solves this. I have my monitors, keyboard, mouse, ethernet, etc all plugged into a TB docking station. Then a single TB cable I swap between my work machine (Macbook Pro) and personal machine (Razer Blade).

My setup is a little different but it's reliable and simple: Dell UltraSharp U3417W has built in usb hub. I can connect pc and laptop to this monitor and switch between them with monitor button. Connect keyboard and mouse to monitor (and connect upstream usb cable to pc/laptop) so your keyboard and mouse move with your monitor switch. This setup only use one monitor but it's enough for my use. I have another regular 1080p monitor that always connect to one machine.

I use a Dell D6000[0] to drive 2x 1440p monitors, my keyboard and mouse via a single USB-A/C cable swapped between personal and work machines. It does it all via DisplayLink software so it adds a little load to the computer, but not noticeable. I've used it with Dell laptops, Surfaces, can even power (slowly) a MBP.

My desktop doesn't support Thunderbolt, which rules out the vast majority of solutions I've looked at.

[0] https://www.dell.com/en-us/work/shop/dell-universal-dock-d60...

Remember when we had different connectors for different purposes and it was easy to tell what a given connector or cable did? I do, and I think USB-C is a massive backwards step in usability.

It didn't have to be. If only there was some foresight into standardizing a marking system to indicate capabilities of cables and ports. And possibly reduce the number of options available based on educated guesses on use cases and cost drivers. Right now there's no way to determine what voltages a PD port can supply, what voltages a device requires to be able to charge, what amperages each one is capable of handling, if the cable is capable of data, what data rates are supported, if a port can output video, which standards it can output in, and on and on and on. Instead of coming with the labeling genius that is USB 3.2 Gen 2x2 (pop quiz, is that better/worse/compatible with USB 4 3x1?), a marking scheme for capabilities would have been nice.

What would be really helpful is a doohickey that you can plug into a USB-C/TB port and it tries to negotiate all power options and data speeds and video modes, and then tells you which ones that port supports.

Add another doohickey, or incorporate it into the first, that has two ports. You plug a cable into both, and it tells you what the cable supports.

How is all that an improvement over separate cable and port shapes?

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