Hi folks,
Recently bought a single monitor level1techs DP 1.2 1-monitor switch, and I have a first-world problem with it. I don’t expect anyone to know the answer, but juuuuust in case.
I have a Lenovo M93P SFF system that I’ve turned into a Hackintosh. It’s a nice little machine that has 2 DisplayPorts and lots of USB3 connectors, and everything works ok on it. I can connect it to a monitor via one of the DP ports and to mouse and keyboard via USB, and it works fine, and even sleeps. When waking from sleep with a keypress the monitor “wakes up.” USB works just fine, etc. A-OK.
When I connect the system to the monitor and to keyboard and mouse using the KVM, everything works fine as long as a) the machine is booted when the KVM selector is switched to the Hackintosh and b) the switch is never changed. When the switch is changed, it works fine to change to another system, but when we attempt to switch back to the Hackintosh, there is no display. The same symptom happens if we boot the Hackintosh connected via the KVM and switched to it and select “Sleep” from the Apple menu. The display never comes back, although the computer is accepting keyboard input at least because I can hear it beeping when I annoy it by pressing lots of keys.
The Hackintosh boots fine when connected to the KVM but the KVM is not switched to it, but when it’s switched to, it has the same problem of no display.
The monitor is a Dell U2713HM (its specs say it’s DP 1.2; it cannot be switched to any other mode in firmware).
I have switched cables around, and isolated the problem such that there are only two known-working sets of USB/DP cables involved, ones from the monitor to the KVM and ones from the KVM to the Hackintosh. The same sets of cables work fine to switch from and to a single connected Ubuntu Linux machine.
The cables are all generic DP 1.2 cables (yes, I know… but they do indeed work fine in the same role for both a Windows system on exactly the same hardware and an Ubuntu Linux Thinkpad).
There is only one Mac setting that is vaguely related in the System Preferences (“Prevent computer from sleeping when display is off”), which is enabled (it’s prevented from sleeping when the display is off).
EDIT later: I should note that I can fool the system into displaying something when connected to the KVM by disconnecting the DP cable from the Hackintosh first DisplayPort, waiting ten seconds, plugging the DP connector in to the computer’s second DisplayPort, waiting ten seconds, then removing it from the second DisplayPort, waiting another ten seconds, then plugging it back in to the computer’s first DisplayPort. Just disconnecting it and reconnecting it from the first DisplayPort has no effect, no matter how long I wait before plugging it back in.
Aaaanyway. Just a hail mary to see if anyone has any ideas. Thanks for a great KVM!