9.7.5 AXI protocol
The ACP is AXI compliant, but not does support the full protocol.
The following AXI protocol restrictions apply:
- The APROT input
is ignored and the APROT output is always LOW
on the AXI master buses and the AXI peripheral bus.
- Only swap-like accesses are accepted, that is, a
locked read followed by a nonlocked write. AWLOCKSC is
not forwarded from the ACP to any master ports on AWLOCKM0 or AWLOCKM1.
These ports are always LOW.
- The ACP does not support exclusive accesses, and
there is no exclusive monitor. If either master attempts an exclusive
read, the ACP returns an OKAY response instead of an EXOKAY response.
The master can treat this as an error condition, indicating that
the exclusive access is not supported. ARM recommends that the master
does not perform the write portion of this exclusive operation.