I have a PC with a DisplayPort monitor. When the monitor sleeps or is powered off, the OS loses track of the current display resolution. My research indicates this is probably due to the Hot Plug Detect (HPD) pin being brought low when the monitor enters sleep mode or is powered off. To remedy this, I'd like to have DisplayPort's (DP) hot plug detect (HPD) always report that it is connected.
For HDMI, there's a device that puts a 1K resister between the power and HPD pins. I think something similar would work for DP. I can't find any easy-to-open DP to DP adapters but maybe I can hack a cable.
Further research indicates that in DP 1.1 there is a power line but it's not available in DP 1.2. (The specs seem to say that the power is connected at the port but cables should not pass it through in DP 1.2 like they would in DP 1.1.)
USB seems a viable alternative for power but HPD uses a 3.3V supply while USB is 5V. Since it's a cable hack, I think keeping the component count down is necessary. Maybe a zener diode based regulator would do the trick, sort of like this:
Spice simulations seem to indicate the voltage would fall within what is necessary to pull up the HPD.
So far this is all theoretical. I don't have access to the official DP specs (or the official USB specs for that matter) and I'd rather not fry my video cards or monitor.
I'm hoping there's someone familiar with DisplayPort here that can either tell me if this is likely to work or can point me in the right direction.
(Using other video connection types is not an option.)