Macbook 2015 12inch Retina with USB-C

[Carlo]

Thank you Paul,

Very useful information.
This is not dissimilar from my experience with the multi port adapter. It's not behaving consistently and in my case was quite picky on the power output as well.

From what I've seen so far, USB-C with alternate mode and power delivery is very tricky to get right. We'll continue to run tests but the first hand experiences from the forum as invaluable.

Carlo

[paultzirides]

So maybe I spoke too soon. I've been using the Plugable dual-display adapter connected to the Apple adapter for a couple days now, and I have some updates on expected vs. observed behavior.

My MacBook is set NOT to sleep, but the displays turn off after 5 minutes. After coming back, the internal display does NOT light up as expected, but the external displays do (Monitor > HDMI on Apple adapter, as well as monitor > Plugable adapter). Unplugging the Apple adapter and plugging back in again causes everything to go back to normal. This is keeping in mind that the Plugable adapter is connected to the USB port on the Apple adapter.

Based on what I have experienced in the past, this is new behavior. Typically, when everything comes flooding back at once, things get weird, but it looks like simply unplugging the Apple adapter (and thus the connected Plugable adapter) and plugging it back in sets everything right again. Thankfully, this is a super easy fix, and not really a nuisance since we would have to do this constantly with the Dell docks anyway.

I will most likely be picking up a Plugable triple-display adapter based on my experience with their other products, and because it seems to strike the best balance between convenience and function. Based on my experience with the Apple adapter, I feel confident that this one will work consistently enough to not be a bother.

Thanks for all your support and hard work! Keep the updates coming

[Carlo]

We have run tests with a number of USB-C adapters and USB products with a 2016 MacBook without encountering particular USB issues.
We're going to test the 2015 MacBook next: the USB host controller is different.

We've observed the same issue Paul found: in systems with recent Intel GPUs sometimes the internal screen does not resume from sleep when USB screens are connected.
The same happens sometimes on warm reboots and we've seen a similar behaviour logging out and in again.
This is a Sierra issue not depending on USB-C but since all MacBooks have a single recent Intel GPU, they are all potentially affected.

If you see this issue please open a bug with Apple: this is the last severe issue not yet fixed in the latest Sierra beta!

Best regards,
Carlo

[wahlfeld]

Originally Posted by Carlo

We have run tests with a number of USB-C adapters and USB products with a 2016 MacBook without encountering particular USB issues.
We're going to test the 2015 MacBook next: the USB host controller is different.

We've observed the same issue Paul found: in systems with recent Intel GPUs sometimes the internal screen does not resume from sleep when USB screens are connected.
The same happens sometimes on warm reboots and we've seen a similar behaviour logging out and in again.
This is a Sierra issue not depending on USB-C but since all MacBooks have a single recent Intel GPU, they are all potentially affected.

If you see this issue please open a bug with Apple: this is the last severe issue not yet fixed in the latest Sierra beta!

Best regards,
Carlo

Not good that you're seeing issues too but it does make me feel better than it's a genuine problem and not something wrong with my device. It's great to see you and team working on this Carlo! I managed to get my hands on another USBC adapter to USB3/HDMI/SD card etc (forgot to check the brand) but I experienced the exact same behaviour as mentioned in my previous comments.

Keen to hear how you go with the 2015 Macbook testing.

Curtis

[Carlo]

Originally Posted by wahlfeld

Not good that you're seeing issues too but it does make me feel better than it's a genuine problem and not something wrong with my device. It's great to see you and team working on this Carlo! I managed to get my hands on another USBC adapter to USB3/HDMI/SD card etc (forgot to check the brand) but I experienced the exact same behaviour as mentioned in my previous comments.

Keen to hear how you go with the 2015 Macbook testing.

Curtis

OK so this has not been too easy for Kamil who tested here. This configuration is quite flaky in our tests.

There is definitely an issue. What we see happening connecting a USB 3 device to the Apple adapter connected to the MacBook is that sometimes only the USB2 part of the USB hub in the dock is enumerated.

Interestingly the OS then tries to re-enumerate and sometimes succeeds after 1-2 minutes. And sometimes the whole USB bus hangs. By inserting "slowly" the USB 3 cable in the adapter the chances of success increase (probably the adapter is sensible to the VBUS timing).
After noticing this, we went back to the 2016 MacBook and saw that the same was happening but the recovery is always succeeding for that model.

This is reproducible with other USB 3 devices so I'm not sure Targus could do something about it.

So not great unfortunately.

In your situation a possible workaround could be to use a USB 2 cable between the Apple adapter and the dock. This would be more reliable.
You would lose bandwidth but up to two 1080p screens it should be fine: we don't needlessly waste bandwidth as other technologies do (ahem...).

Best regards,
Carlo

[wahlfeld]

Originally Posted by Carlo

OK so this has not been too easy for Kamil who tested here. This configuration is quite flaky in our tests.

There is definitely an issue. What we see happening connecting a USB 3 device to the Apple adapter connected to the MacBook is that sometimes only the USB2 part of the USB hub in the dock is enumerated.

Interestingly the OS then tries to re-enumerate and sometimes succeeds after 1-2 minutes. And sometimes the whole USB bus hangs. By inserting "slowly" the USB 3 cable in the adapter the chances of success increase (probably the adapter is sensible to the VBUS timing).
After noticing this, we went back to the 2016 MacBook and saw that the same was happening but the recovery is always succeeding for that model.

This is reproducible with other USB 3 devices so I'm not sure Targus could do something about it.

So not great unfortunately.

In your situation a possible workaround could be to use a USB 2 cable between the Apple adapter and the dock. This would be more reliable.
You would lose bandwidth but up to two 1080p screens it should be fine: we don't needlessly waste bandwidth as other technologies do (ahem...).

Best regards,
Carlo

Damn, not good. Happy to try what you suggested Carlo, but I'm curious as to what is the root cause here? Is this a limitation of USBC? Are there any Windows devices with USBC that exhibit the same behaviour?

[Carlo]

Originally Posted by wahlfeld

Damn, not good. Happy to try what you suggested Carlo, but I'm curious as to what is the root cause here? Is this a limitation of USBC? Are there any Windows devices with USBC that exhibit the same behaviour?

In theory everything should be working OK. And it does even with this MacBook for many use cases.

However I can imagine that USB C, especially when the new "alternate modes" are used to carry other completely unrelated signals like video or Thunderbolt, is very new and may have teething issues for some use cases.
In this case the issue may be in the USB C adapter, in the MUXes that separate video out or on the host controller. The next step would be to connect a USB analyser between the adapter and the machine but I suspect the issue is probably in the MUXes and relative logic.

This is just my personal theory given the evidence so far.

Regards,
Carlo