Setting up QOS diffserv on GS752TPv2 and M5300-28GF3

We are trying to set up QOS on our switches and from reading the KB article it says to check all the interface ports to configure it on.  I'm just checking to see if all means every port or if just the ports that will have a voip phone plugged into it.  The switches also have cameras, computers, and other network devices plugged in them.  Thanks for your help.