Grammatically speaking, "coding data" implies that something is done to the data; applied to the data. Data are being coded; they become en-coded. However, qualitative researchers also use the term "coding data" when they describe processes in which they generate codes with, or from data. I think this is confusing.  The term "coding data" characterizes one end on a continuum of coding practices: coding as sorting. When we describe how we build or reconstruct systems of meaning by analyzing data it may make more sense to say that we're "data-ing codes".