On 06 Jan 2021 at 16:41:25 GMT, Theo 
wrote:

> Chris Green  wrote:
>>  Andy Burns  wrote:
>>  > The Pi is the HDMI source, and the monitor is the HDMI sink, per the
>>  > spec the 5V power should be supplied from the Pi to the monitor, not the
>>  > reverse ...
>>  >
>>  I've heard it said that the HDMI spec is a real can of worms.
>>
>>  This thread is just another thing that increases my dislike of HDMI.
>
> It's exactly the same with VGA.
>
> The purpose of this is for the computer to read the EDID ROM from the
> monitor.  It supplies 5V to allow detection of the connected monitor even if
> it's turned off.
>
> The monitor/KVM should not be emitting power on this rail.

I shutdown the Pi and when it had, turned off its power at the switch on the
socket strip. This caused the green-LED fluttering I mentioned before. I then
disconnected the HDMI cable from my Mac (the cable that goes to the other
input of the KVM unit). The green and red LEDs on the Pi then went out.

So it's my Mini that's doing this, but that is perhaps not surprising given
what I've learnt in this thread.

--
Tim

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