Unfortunately, the HDMI connector on the (otherwise amazing) pipistrello board (http://saanlima.com/store/index.php?route=product/product&product_id=51) cannot be used as an input.
The HDMI clock pins must be connected to global CLK pins for HDMI input to work and they are not. This basically means that Pipistrello can't be used for HDMI input unless you are willing to do some board rework. The HDMI SDA and SCL signals from the connector go to GCLK pins. By removing the I2C level translator chip you can run two wires from the HDMI connector to the I2C chip pads. This way the HDMI clock pins can be routed to GCLK pins without any trace cutting.
This is a fairly delicate rework and needs steady hands, but I've done it successfully to both my pipistrellos. You then need to reroute the SDA and SCL signals to a generic I/O, which is fairly straight forward. In the photograph you can see how the hack looks like, but I could write/record a guide if people are interesting in modding their boards.