AHB LOCKED Transfer

LOCK tells the arbiter to keep the current master granted, SPLIT tells the arbiter to grant another master, so the only possible action the arbiter can take for these contradictory requests is to grant the dummy master that must exist in any system with SPLIT capable slaves.

The dummy master will only perform IDLE transfers (i.e. no data transfers), so cannot corrupt the LOCKed sequence that is ongoing.

When the original slave is able to complete the SPLIT transfer, it will signal this to the arbiter on HSPLIT and the arbiter can then re-grant the original master, and the LOCKed sequence can then continue.

However as the slave has an HMASTLOCK input telling it that the current transfer is part of a LOCKed sequence, it should know that there is no system advantage in returning a SPLIT.

So yes, a slave can return a SPLIT response to a LOCKed transfer, and the arbiter must then grant the dummy master, but the slave should use the HMASTLOCK input to see that a SPLIT response is not useful at this time.