Bump!
I know it's 4 years later, but still, bump.
I'm on a i.MX8MP, so I have a M7 in baremetal and the 4x A53 cores running Linux. In the baremetal I can use:
MU_Init(MUB);
NVIC_SetPriority(MU1_M7_IRQn, APP_MU_IRQ_PRIORITY);
NVIC_EnableIRQ(MU1_M7_IRQn);
MU_SendMessage(MUB, regIndex, msg);
MU_ReceiveMsg(MUB, 0, &msg)
In Linux, I got nothing. I understand I could run the A53 cores in baremetal too and then the send/receive messages would work, but is there something in Linux? Even the VPU application notes (RM00294) refers to the Linux Reference Manual (RM00293), which contains nothing useful. My understanding is that one could simply call request_irq() with the right irq number (88 in my case) and a handler. But <linux/interrupt.h> doesn't exists.
Anything happened in there in the last couple years?