> 4) Is there a simple command that I can issue to the CP to clear the
> screen JUST to see if it is issuing any commands from the ring buffer
> at all?
You could do something along the lines of radeon_test_writeback: write
to a scratch register via the CP and verify by reading the register
directly. Actually, doing something like that from radeon_do_init_cp and
returning an error if it fails might generally help to handle CP
initialization issues more gracefully.
> 1) The fglrx driver never sets the (RADEON_CP_RB_RPTR_ADDR) register.
> If I read the register back when fglrx is running, it is set to "0".
> What does that register indicate?
You can ignore scratch register writeback for now. You may want to load
the radeon kernel module with no_wb=1 though to prevent the unlikely
event that it intervenes with anything.