P.C.'s note choicees on So What were discussed at great length in an older thread.
This one? His lines over the bridge do seem to suggest Db Major, which is somewhat perplexing, but if you listen to everything else that's going on, including the melody, it's obviously Eb dorian.
When you are first learning to walk over one chord for many measures, it is important to place your roots in strategic locations. IOW, don't start off taking a bunch of liberties with any note that strikes your fancy, or where your hand happens to wander. At the very least, you should put a root on the downbeat of every section. Better yet, every four bars. Better still, every other bar, and alternate with the fifth as target note. By doing this, you will help yourself as well as the rest of the band by defining the form, and not getting lost.