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The VGA->DVI->HDMI chain retained the following simplicity of: 1. Send color of pixel 2. At the end of the line + blank send a pulse on HSYNC pin 3. At the end of the screen send a signal on the VSYNC pic. That's it (almost, there's EDID). If you can implement this, chances are you can display what's sent down the cable accurately. Likewise with audio, you just send a voltage level down the cable, if you want to be fancy, you use SPDIF, in which case you send a 16-24 bit number per channel.
That's it, no handshake, no negotiation.
I have a TB dock for my Macbook. Sometimes it doesn't register. Sometimes it reboots for some reason, giving me 10 seconds of black screen. There's a 10% chance on every connect or reboot that it will just plainly not work.
And it's way better than it used to be, but still pretty bad.
The thing is, the old protocols all have their limitations.
Analog audio - unless it's balanced - is highly vulnerable to all sorts of external interference. S/PDIF is normally two channels of PCM audio (that's decently easy), but it can carry up to 8 channels of variously compressed audio and not every sink or source supports all possible codecs (thanks to software patent licensing BS). In either case, 48 kHz sample rate and 20 bits precision are the fundamental limits.
For video... analog maps well to CRT displays but reconstructing signals from analog inputs in a TFT/LED screen is inherently a lossy process, and running anything more than 1080p is a gamble and requires good, short cables. And digital video at higher data rates becomes a nasty mess and practically devolves into RF black wizardry at the kind of stuff you can pull off with modern digital video signalling - 4K @ 240 Hz refresh rate, this is utter insanity if you just think how much data is being shovelled around.
1. Plug the phone into hub.
2. Check that you get display output, the mouse and keyboard are working whilst the screen is not turned off and the phone is not locked.
3. Lock the screen and wait for the screen to turn off, thereby mimicking suspend.
4. Try to make the phone resume by using the attached keyboard and/or mouse.
If all goes well, the monitor should turn on after unlocking the phone or using the keyboard / mouse.
# Other things to try
Again try and reproduce the issue with a Samsung tablet that supports display out via USB C.
Connect the keyboard via Bluetooth and try to make the laptop resume. I found that connecting a Keychron keyboard via bluetooth allowed me to resume a Macbook Pro. I was kinda surprised that this worked.
Does the same issue occur on Linux as well?
I guess you could attach a USB packet type of debugger to ensure that data is being sent to the laptop by attaching the debugger to the cable that connects to the host machine. If you see USB traffic when the monitor goes to sleep and you are pressing keys in the keyboard and the dock still has power that means the dock is working fine so you can rule that out.
It's a cheap phone with a USB-C port that works at USB2 speeds and the dock uses display-link but go figure.
I read a few of your other posts and your writing style is direct and pleasant in a way I appreciate. Thank you for actually writing things.
Fabien Sanglard's HN handle is fabiensanglard
In addition, it takes some time for Apple to squash bugs after releasing new hardware or software. M5s used to be unreliable with Anker TB4 until 1-2 months ago.
Meaning - anything could be the device preventing what you expect to happen, even if it looks like it should be impossible and have nothing to do with it.
Which device just woke every other device up at 4am?
Which device just shut everything down while I was in the middle of a movie?
And are they the same device?
Turns out it was that.
Then my comment won't help you much: since I swapped my MacBook Air M1's 27" monitor for a 34" one from the same brand, it's only been the exact clusterfuck of unreliable "wake up not working properly anymore" for no friggin' reason. Except in my case it was working fine, and now it's not anymore.
I take modern USB-C Flash Drive, plug it into my Mac. Nothing. Take it out, plug it in again, and it mounts just fine.
Same with SD Cards.
I have no idea why this is, and I'm not sure if it's always been this way, but I can't remember a time when I didn't have to do this.
My Macbook Air + LG Ultrafine combo works flawlessly.
A brand new Ryzen 9 system + recent model AOC monitor, on Windows, using DisplayPort, refuses to come back from sleep every single time.
I think monitors are a sweet spot - they tend to stick around longer than computers, and docks really don't need to change a lot over time, at least now with thunderbolt out there. Fewer cables, too.
I like the idea of standalone docks, and I purchased a few, but none reliably worked for me.
look for dell monitors with kvm
Additionally, if you look at the firmware updates they published for the successor U2725QE you'll see things[0] again not specific to Macs like
* resolves monitor wake-from-sleep issues; and * resolves daisy-chained monitors not waking from standby;
Which may not be exactly the same bug, but probably is & it shows the problems are getting addressed in Dell's own firmware
[0]https://www.dell.com/support/home/en-us/drivers/driversdetai...
While most users know the power trick by now, there are still those in the "not my job" and "any excuse is a good excuse" categories, and for those I might just spend a little on old fashioned power timers.
They sent me a replacement and I had the same problems. Then found out it was a design problem not a manufacturing one. They could send me 10 more and they would still not wake up all the ports properly. I don't even recall now what series of ritual steps I took to wake it up. I think unplugging it completely from everything. Which is actually more cable wear than not having a dock.
Last time a firmware update came out I couldn't run it from my Lenovo laptop. I had to use a non-Lenovo one. Really made me angry about their quality control.
Next to that the dock has this weird behavior when the laptop is asleep, the monitors wake up every 5 minutes.
[1]: https://www.8bitdo.com/retro-mechanical-keyboard-m/
My chances of getting new monitors are slim in this climate but it's a new avenue of investigation at least.
What seems to work reliably is monitors directly into the MacBook Pro via HDMI and USB-C, keyboard, mouse, audio into the OWC Dock.
any benefits in coding and reading hackernews
Learning this lesson (on the unreliability of systems using a very expensive docks) cost me over $1200 in chopping and changing hardware in the last few years.