There's a very odd but predictable sequence of events that breaks Wi-Fi
when using both cores:
1) CPU1 calls pendsv_suspend() - for example sleep() causes
a softtimer node to be inserted, which calls pendsv_suspend().
2) CYW43 sends wakeup IRQ. CPU0 GPIO IRQ handler schedules PendSV
and disables the GPIO IRQ on CPU0, to re-enable after
cyw43_poll() runs and completes.
3) CPU0 PendSV_Handler runs, sees pendsv is suspended, exits.
4) CPU1 calls pendsv_resume() and pendsv_resume() sees PendSV
is pending and triggers it on CPU1.
5) CPU1 runs PendSV_Handler, runs cyw43_poll(), and at the end
it re-enables the IRQ *but now on CPU1*.
However CPU1 has GPIO IRQs disabled, so the CYW43 interrupt never runs
again...
The fix in this commit is to always enable/disable the interrupt on CPU0.
This isn't supported by the pico-sdk, but it is supported by the hardware.
Fixes issue #16779.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
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