ZHCSGV2J June 2009 – January 2017 OMAP-L138
PRODUCTION DATA.
Interrupt nesting occurs when an interrupt service routine re-enables interrupts, to allow the CPU to interrupt the ISR if a higher priority event occurs. The AINTC provides hardware support to facilitate interrupt nesting. It supports both global and per host interrupt (FIQ and IRQ in this case) automatic nesting. If enabled, the AINTC will automatically update an internal nesting register that temporarily masks interrupts at and below the priority of the current interrupt channel. Then if the ISR re-enables interrupts; only higher priority channels will be able to interrupt it. The nesting level is restored by the ISR by writing to the nesting level register on completion. Support for nesting can be enabled/disabled by software, with the option of automatic nesting on a global or per host interrupt basis; or manual nesting.