[Arm-netbook] HDMI v1.4 Audio Return and Ethernet channels

Richard Wilbur richard.wilbur at gmail.com
Tue Aug 1 06:57:54 BST 2017

On Mon, Jul 31, 2017 at 11:45 PM, Andrew Bolin
<fivepointpalmexplodingheart at gmail.com> wrote:
> Can't use it if the pin has no connection to the CPU!
> In the last screenshots I saw (
> http://hands.com/~lkcl/eoma/a20_hdmi_review/scrn2.png ), pin 2 HEAC+
> (ethernet/ARC) is not connected to anything. Pin 1 (HEAC- & HPD) does go
> somewhere, but it's of no use for these functions by itself.

I agree, sounds like HEAC (HDMI Ethernet/Audio Return Channel) won't
work as we don't have the pair connected to the CPU and that signal is
HEC -- differential, ARC -- single-ended.

On the other hand HPD (Hot-Plug Detect) should work.

> CEC does seem to be routed and is mentioned on the A20 info page.
> No SBC that I've seen actually uses these functions (unfortunately).

We'll have to see if we can make it work.

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