You only really need to worry about if you are playing with HDCP video encryption.
If you just use or buy an IC HDMI transmitter, you are ok.
If you make a product with said IC to transmit HDMI, so long as you do not use the HDMI logo or state it is 'HDMI x.x compliant', you are ok.
To get the right to use the HDMI logo and the right to say you are compliant with one of it's standards, you must pay and get your hardware tested to the hill before you are allowed to do so.
If you had to ask this much, HDCP is in a completely different league, stay away... If anyone offers you an IC which says it can encrypt / decrypt HDCP, do not waste your time.