Transmission of arbitrary data through an HDMI port

Question

There seems to be something of a trend these days to fail to equip cheap consumer laptops with decent expansion capabilities: no ExpressCard slot, USB 2 (not 3), no eSATA port. However, HDMI ports are still fairly common on such machines (at least on mine). HDMI's max throughput is 10 Gbps, well above either USB3 (4800 Mbps) or eSATA (6000 Mbps). Is it (theoretically) possible to use an adapter (and, presumably, a custom driver) to make the HDMI port function as a USB3 or eSATA port, enabling such a machine to use newer external hard drives at full speed?

I would want to do this under Linux, but am equally interested in knowing whether it's possible under any O/S.

Answer 1

I doubt that the hardware gives direct access to the HDMI port in a way that arbitrary data can be moved through it. The hardware that generates the HDMI signal (analogous to the RAMDAC in analog VGA video cards) is likely directly connected to the video RAM and no interface to program it exists. It's even less likely given the whole thing these days with HDCP; giving a programmer direct access to the HDMI signal generator would be a way to disable HDCP and it would make the **AA mafia a bit angry.

Never know though; perhaps there's undocumented GPU assembly instructions that put the signal generator in a programmable debug state or something...

Answer 2

HDMI 1.4 adds an Ethernet channel to the cable, but I don't believe that there are yet any peripherals that put anything at the end of it, nor that such a device would be cheaper than a normal Ethernet device that does the same, nor that a "cheap consumer laptop" would even have a 1.4 port in the first place.