The predictions of voter photo ID suppressing the vote have not come to pass. In fact, early voting numbers are way up in Tennessee.
In this Chas Sisk article though, those claiming the photo ID suppresses the vote say the high early voter turnout is because people want to be sure their photo IDs work, so they are coming out to vote early. They also point to areas that Obama previously won or did well in are not turning out to vote near as much as they did 4 years ago, again inferring its because of a lack of photo ID in those communities.
Yes, I am sure those are the factors. The IDs. Riiiight.