USB-C Video Port not working with MacBook or other laptops

Philips_Support_P · February 5, 2020, 2:32pm

Not tested yet, mass production was already going on when the 16" MBP was released. Maybe I need to go to the Apple store and test it out there.

wernerj · February 5, 2020, 2:33pm

Yeah! And you might just happen to expense an upgraded 16" machine “for compatibility testing”

Philips_Support_P · February 5, 2020, 2:35pm

Haha, never ever. Waiting for the 14" to come out.

@PEHowland according to Use multiple displays with your MacBook Pro (16-inch, 2019) - Apple Support you shouldn’t plug in video devices to the same bus.

So: have you plugged any other USB-C devices to your laptop? If yes, can you check with just the picopix plugged in? Can you also check with the MacBook charger plugged into the opposite side as the picopix?

wernerj · February 5, 2020, 3:21pm

That’s only for the high-resolution screens, but still a good recommendation. I’m running a USB3.1 superspeed USB-C hub and the USB-C DP Dell 3840x1600 screen from the same side on mine with no issues.

I had to do some research as to why the older Mini-DP to HDMI adapters didn’t work with my USB-C to Mini-DP alt-mode dongle. Turns out that the Mini-DP plugs were in fact DP++. The HDMI alt-mode should enable the same thing in the GPU as the DP++ HDMI detection. Barco summarized the DP++ thing nicely here (this was obviously written before HDMI alt-mode was standardized):

trappm · February 5, 2020, 4:36pm

Apart of the Macbook, I have the same observation on my MiBook Air under Windows 10 using the provided USB-C cable. When connecting the cable a second display shows up in the Windows screen options but when selecting mirror screen, then the projector still shows “no signal”. So the issue seems to be the same…

PEHowland · February 5, 2020, 4:59pm

OK - to add to the mystery:

I confirm that I don’t have other USB-C devices connected, and that I am connecting the video connection on the other side of the MacBook from the power
More peculiar: I have just connected a USB-C docking port to my MacBook Pro (which includes additional USB-C ports, USB-A port, card reader slots and an HDMI connector) and used this to connect to the projector using an HDMI-to-HDMI cable. The projector displays the MacBook display fine. So if I go from USB-C to dock, then dock HDMI to Projector HDMI it works. (For fun I also tried USB-C to dock, then USB-C on dock to USB-C on projector, but that didn’t work).

trappm · February 5, 2020, 6:54pm

Again, same observation on my MiBook Air with Win 10. - USB-C dongle to HDMI works without any problems. - USB-C to USB-C Input for PPM equals no signal.

wernerj · February 5, 2020, 7:12pm

The USB-C to HDMI dongle most likely a DP alt-mode dongle with an additional DP to HDMI converter inside. The projector only supports straight up HDMI alt-mode. This alt-mode has been standardized since 2016 (and has been well supported by MacBooks) but there are clearly a lot of computers not supporting it still. Using the PPM HDMI input is a workaround that won’t affect image quality, but I agree that a USB-C full featured cable and nothing else is a more portable solution than a dongle and an HDMI cable…

trappm · February 5, 2020, 8:38pm

Since the USB-C to HDMI dongle is working it seems that it is some kind of protocol issue, right ? Since the dongle is working and the direct USB-C connection isn’t it is not data rate related, since HDMI or DP should have the same video data rate. If your suspection is right, why is PPM only supporting one mode, and not both ? - Would it be fixable by SW, or is it some HW issue ? - We are facing a lot of strange incompatibilies with the PPM, that are not easing normal usecases. For a portable device it would be cool not to mess around with a lot of extra gadgets to make data paths towards video, audio, decoding or charging working.

wernerj · February 5, 2020, 9:23pm

This is not something that can be patched in PPM software. Basically the V56 chip in the PPM has three HDMI inputs, one from the internal Android SoC, one from the HDMI port and the third from the USB-C video port. The chip doesn’t know how to deal with DisplayPort data. If the PPM was to support DP alt-mode there would have to be a DP to HDMI converter chip inside as well.

HDMI alt-mode is a fully standardized alt-mode that most-if-not-all devices capable of DP alt-mode should be able to do (as most GPUs can do DP++ HDMI-over-DP), but if it’s not currently present on the sink side that’s something that will require firmware changes there. The 16" MacBook Pro seems to have this issue at the moment (the older machines works fine).

kugiigi · February 6, 2020, 5:50am

So it is confirmed PPM uses HDMI alt-mode?
That’s sad because I thought DP alt-mode is more common with devices.
Maybe that’s the reason why Samsung S8 won’t work. I never expected that HTC 10 supports HDMI alt-mode though. Now I’m not sure if my coming PinePhone will work on PPM

wernerj · February 6, 2020, 7:23am

Yes. USB-C Video Port not working with MacBook or other laptops - #21 by Philips_Support_P

DP alt-mode would have required yet another chip or two in the PPM, driving cost up. That’s my guess.

Edit: The only video alt-mode supported by the PPM USB-C video port is alt-mode DP, not HDMI → Connecting laptop using USB-C cable - #21 by Philips_Support_P

kugiigi · February 6, 2020, 7:26am

I see. HDMI costs royalties too right? DP is free?

wernerj · February 6, 2020, 7:34am

There’s already an HDMI port right next to the USB-C so it won’t really matter but yes I believe you’re right about DisplayPort being royalty free. It would be a hard sell only presenting DP and DP alt-mode without HDMI though.

aafarup · May 3, 2020, 11:23am

Guys I used the provided USB-C with PPMAX to connect to macbook and it works fine. ( the apple charging cable doesnt work though as its just a charging cable)

I am trying to run auto focus and it is re focusing but cant see the focus ring with letters to fine tune it when connected to USB-C Video output. Is it normal? Any Expert opinion?

IvoGrijt · May 3, 2020, 11:33am

This is normal, it is still focusing but on the image displayed as is. The focusing ring is an Android app which is why you don’t see it when using one of the external inputs.

LLG · May 3, 2020, 3:41pm

If it’s easier for you, you can do focus on the main screen (with the on purpose screen) and then go back to your USB-C source .

aafarup · May 3, 2020, 4:39pm

yeah i did that way , just wanted a confirmation

wernerj · May 6, 2020, 11:54am

Just to clarify, it was confirmed from engineering (Connecting laptop using USB-C cable) that there_is_ DP to HDMI conversion built in, and I have now verified myself that there is in fact a classic Parade PS176 protocol conversion chip between the USB-C video port and the HDMI multiplexer in the V56.

kugiigi · May 6, 2020, 11:57am

so that means only alt-mode HDMI will work and not DP?