rp2: Enable SEVONPEND CPU interrupt bit.

projectgus · projectgus · commit 1ca5e66e435c · 2023-11-30T17:10:15.000+11:00
Previously this was not set, so potential for race conditions in interrupt
handlers this didn't issue SEV. (Which is currently all of them, as far as
I can see.)

Eventually we might be able to augment the interrupt handlers that wake the
main thread to call SEV, and leave the others as-is to suspend the CPU
slightly faster, but this will solve the issue for now.

Signed-off-by: Angus Gratton &lt;angus@redyak.com.au&gt;
diff --git a/ports/rp2/main.c b/ports/rp2/main.c
@@ -73,6 +73,9 @@ bi_decl(bi_program_feature_group_with_flags(BINARY_INFO_TAG_MICROPYTHON,
     BI_NAMED_GROUP_SEPARATE_COMMAS | BI_NAMED_GROUP_SORT_ALPHA));
 
 int main(int argc, char **argv) {
+    // tickless port, interrupts should always trigger SEV
+    SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
+
     #if MICROPY_HW_ENABLE_UART_REPL
     bi_decl(bi_program_feature("UART REPL"))
     setup_default_uart();
