So if you disagree that qualia is a basic fact of physics, what do you think it reduces to?

Something brains do, obviously. One way or another.

And if you think physics can tell whether something is a Turing-machine-simulating-a-brain, what's the physical algorithm for looking at a series of physical particles and deciding whether it's executing a particular computation or not?

I should perhaps be asking what evidence Searle has for thinking he knows things like what qualia is, or what a computation is. My statements were both negative: it is not clear that qualia is a basic fact of physics; it is not obvious that you can't describe computation in physical terms. Searle just makes these assumptions.

If you must have an answer, how about this: a physical system P is a computation of a value V if adding as premises the initial and final states of P and a transition function describing the physics of P shortens a formal proof that V = whatever.