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TDA4VM: IPC: Questions about killing an application using ti-rpmsg-char library

TS L
Intellectual 911 points

Part Number: TDA4VM

when i test IPC between mcu_1_0 and A72,

i kill the user process which read "ti_rpmsg_char" by "read" function,

then A72 output "virtio_rpmsg_bus virtio3: msg received with no recipient"

Question_1:

is ti_rpmsg_char(which running in linux kernel space) consume the IPC data？ and drop it ? if no "user space process"(which read the data by "read") 

because i can not detect mailbox full by "HW_RD_REG32(tx_baseAddr + MAILBOX_FIFOSTATUS(tx_queueId))" in mcu_1_0

Question_2:

i checked datasheet about "MAILBOX_MSG_STATUS_y Register" and found "NUM_MESSAGES(bit2,10)",so the max NUM_MESSAGES value is 7

is mailbox max FIFO depth == 7?

  • +1
    TI__Guru*** 127045 points

    Hi TS L,

    TS L said:
    "virtio_rpmsg_bus virtio3: msg received with no recipient"

    This trace is printed by the Linux kernel virtio_rpmsg_bus kernel module. The trace is seen when the virtio rpmsg transport cannot deliver a message to an end-point. The kernel transport simply drops the message (is processed and dropped, this message cannot be re-delivered).

    1. ti_rpmsg_char is a library in userspace, and reads the data using the rpmsg_char kernel driver's queue. The virtio rpmsg transports adds a message to the respective rpmsg local end-point device's queue using the end-point id _only_ as long as the end-point exists. Killing a user process will destroy the end-point and all future and in-flight messages to that end-point will be dropped.

    2. MAILBOX_MSG_STATUS_y.NUM_MESSAGES field is 3 bits-wide (bit 0-2). The maximum number of messages is actually 4 (max FIFO depth, requires 3 bits) even though the max value from the bits possible is 7. 

    regards

    Suman

  • +1 in reply to Suman Anna
    TI__Guru*** 127045 points

    Hi TS L,

    FYI, I have edited the title of your original post, it is way too generic.

    regards

    Suman