Hi Eddie,
The MAXWAIT value applies to all SDMA transactions i.e. you cannot further program it granularly for EDMA v/s SRIO v/s some other master. QUEPRI is the only place you can really affect the EDMA priority relative to other SoC masters at the SCR level.
Also note that SDMA impacts transactions to L1D, L2, and EMC resources and is not used to access DDR. The DDR2 controller is connected directly to the SCR.