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.

Although it wouldn't have taken much for the Pi to incorporate a diode to
prevent back-powered.  Maybe there are use cases where people want to power
their Pis from HDMI, I don't know.

Theo

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