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IMX7D A7 and M4 communication, RPMSG throghput

Question asked by Nilesh Patel on Sep 30, 2019
Latest reply on Oct 1, 2019 by igorpadykov



We are planning to use IMX7D because of the heterogeneous architecture in which DDR RAM is shared between the two cores, and can achieve the best speed across the M4 and A7 communication.


We have seen some threads to identify communication between A7 and the M4 core using RPMSG but not sure about the throughput of that. Basically we are targeting 5 to 7 Mbps transfer between the core.


We are planing to follow below approaches to achieve this,

  • Set reserved memory to 512MB of DDR RAM between the core
  • Use RPMSG lite to transfer from M4 to A7 and get the data in linux
  • If RPMSG lite getting overhead due to copy from source to destination, we are plan to transfer physical address and data size(offset) to the A7's Linux.
  • Also, If RPMSG not able to achieve that speed, then use predefined address to write by M4 and read by the A7 from the DDR RAM


We are aware about that DDR RAM is single reader and single writer from M4 and A7. So, only one can access it at a time.


Can we achieve high data transfer from M4 to A7 in anyway by taking advantage of shared memory ?