"Now we have a SOC with A7 and A55, which communicate with each other through MHUv3. However, someone has proposed that A7 and A55 share PBX and MBX, and use separate channels to distinguish between transmission and reception. For example, doorbell, db0 and 1 are used for A55 to send to A7, and b2 and db3 are used for A7 to send to A55. Does this support playing this way? My understanding is that there need to be two sets of PBX and MBX, one set is from A55 to A7, and the other set is from A7 to A55"