Hi Jassi,

quoted

+               The doorbell channels should be used with shared memory and

protocol

quoted

+               level acknowledgment if needed.
+

I would avoid this. People might get notions that they have to use shmem
with doorbell -- a trivial protocol might mean doing some fixed action (like
reset) whenever the doorbell rings.

That's right.
i.MX8 using the general purpose interrupt for peripherals. No shmem needed.
e.g. RTC, Watchdog and ON/OFF interrupt.

BTW, this means the peripheral will use mailbox doorbell channels to handle
Interrupts. Is there such user case in kernel we can refer to?

quoted

+Optional properties:
+-------------------
+- clocks :     phandle to the input clock.
+- fsl,mu-side-b : Should be set for side B MU.

Nit: can we call this 'fsl,no-init' ?

Fsl,mu-side-b is more describing HW.

Regards
Dong Aisheng