Acceptable Interrupt Latency in Linux kernel

["Singaravelan Nallasellan" <singaravelann@gmail.com>]

What is the tolerable interrupt latency for the Linux interrupt handler?

I need to write a driver which will require to invoke a function from
other driver
to read the hardware register. That function will send a message to
the firmware in the some other hardware.

The firmware will go into a bus to read the register and return the
value. This firmware generates an interrupt of the completion of the
register read.

So the whole process of register read will take time to know the
interrupt source.

Currently I dont have the exact duration to read a single register. I
am also planning to push the register read to work queue and return
with IRQ handled from the ISR without knowing the hardware
status.There is a potential to mis handle the interrupt.

If I know the acceptable interrupt latency, It will simplify the ISR handling.

Thanks