clear pending ICU interrupts before enabling global IRQ/FIQ (fix rare hang after deep-sleep wake)

[heyongman]

Context / Problem

In a door sensor use case the device spends most of its time in deep sleep and wakes up frequently via GPIO (door
open/close). Under stress (rapid open/close cycles) the firmware would sometimes hang very early during boot.

Observed symptoms:

• The last reliable UART log line is: bk_misc_init_start_type 3 3
• The next expected line (FreeRTOS heap init) such as prvHeapInit-start ... never appears
• This indicates the start type detection finished, but the system gets stuck before completing func_init_basic() /
  before the heap is initialized.

Root Cause Analysis

A deep-sleep wake is not a fully cold boot. Some ICU interrupt status bits can remain latched/pending after wake-up.

During the boot path, intc_init() enables the ICU global IRQ/FIQ relatively early. If any interrupt is already
pending at that moment, the CPU may enter IRQ/FIQ handlers before the OS/heap is ready, which can lead to an
unrecoverable early-boot hang (no further logs after bk_misc_init_start_type).

Fix

In intc_init(), clear any pending ICU interrupt status before enabling interrupt sources and global IRQ/FIQ:

• CMD_CLR_INTR_STATUS
• CMD_CLR_INTR_RAW_STATUS

This prevents immediate entry into interrupt handlers during the extremely early boot stage after deep-sleep wake.

Changes

• platforms/bk7231n/bk7231n_os/beken378/driver/intc/intc.c
  • Add ICU pending interrupt clear at the beginning of intc_init() (before enabling global IRQ/FIQ)
  • Add a comment explaining the deep-sleep wake scenario and why this is needed

Test Plan

• Stress test: rapidly toggle door open/close to trigger deep-sleep wake >= 100 cycles (Set a short time to deep-sleep, approximately 3 seconds.)
• Verify UART logs: no more cases where output stops at bk_misc_init_start_type 3 3 and heap init log is missing
• Verify runtime behavior: wake -> advertise -> sleep remains stable over long runs without hangs/resets

Risk / Impact

• Minimal change: only clears pending ICU interrupt flags before enabling interrupts
• No behavioral change for cold boot; improves stability for deep-sleep wake scenarios