The language on both product pages (the adapters) appear to indicate DP source to HDMI display only - I am not seeing the reverse explicitly stated.
"Connect your HDMI monitor or HDTV to a DisplayPort equipped computer"
"Supports resolutions up to 1920x1200/1080p"
"Note that this is not bidirectional and therefore will NOT convert HDMI video to mini DisplayPort."
"Connect your HDMI monitor or HDTV to a DisplayPort equipped computer" "Supports resolutions up to 1920x1200/1080p" "Note that this is not bidirectional and therefore will NOT convert HDMI video to mini DisplayPort."