This is the version from his early Gary Clark Jr E.P, 
rather than his new album Blak and Blu.  Though the two versions are similar,
 I do not believe the album version has the main riff which is at the start of the EP.

-------------------------------------------------------------------------------
                             Breakdown (E.P Version) - Gary Clark Jr.
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Tabbed by: Matt


Tuning: Standard
Main riff (intro):
e|-----11-13-11-------------11-13-11-----------|
B|---9-------------8-9----9--------------9-8---|
G|12-----------12v-----12------------12v-------|
D|---------------------------------------------|
A|---------------------------------------------|
E|---------------------------------------------|
Chords:
e|----------------------------------|
B|----------------------------------|
G|6-6-6-8-8-8-8-8-5-5-5-6-6-6-6-6---|
D|6-6-6-8-8-8-8-8-5-5-5-6-6-6-6-6---|
A|4-4-4-6-6-6-6-6-3-3-3-4-4-4-4-4---|
E|----------------------------------|

During the verse, palm mute the root note of each chord and play just that (e.g 4, 
6 and 3 on the A string)

I haven't tabbed the solo, I like to just improvise using pentatonic scales.