arch: arm: cortex-m: Reduce ZLI latency by not disabling them in wrapper
The difference between __irq_disable() and irq_lock() is that the former
essentially translates to `cpsid i`, whereas `irq_lock()` translates to
setting BASEPRI (on cores with BASEPRI). This means that using
irq_lock() does not disable zero-latency interrupts (ZLIs), which
reduces the potential execution latency of ZLIs.
In both isr_wrapper and _arch_isr_direct_pm() (which is just
really an implementation of ISR_DIRECT_PM()), we were using
__irq_disable() to disable all interrups, including ZLIs. But the code
executed with interrupts disabled handles waking up from idle, and so
must only be protected against regular interrupts being executed, not
ZLIs, which should have no effect on the correct execution of the code.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
2 files changed
