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riscv: Clear pending IPIs on initialization

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Even though we no longer call smp_function if an IPI was not sent by
U-Boot, we still need to clear any IPIs which were pending from the
execution environment. Otherwise, secondary harts will busy-wait in
secondary_hart_loop, instead of relaxing.

Along with the previous commit ("riscv: Use a valid bit to ignore
already-pending IPIs"), this fixes SMP booting on the Kendryte K210.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Rick Chen <rick@andestech.com>
This commit is contained in:
Sean Anderson 2020-09-21 07:51:38 -04:00 committed by Andes
parent f760c9a1fd
commit 768502e2a7
1 changed files with 20 additions and 0 deletions
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20
arch/riscv/cpu/cpu.c
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@ -72,6 +72,17 @@ static int riscv_cpu_probe(void)
return 0;
}
/*
* This is called on secondary harts just after the IPI is init'd. Currently
* there's nothing to do, since we just need to clear any existing IPIs, and
* that is handled by the sending of an ipi itself.
*/
#if CONFIG_IS_ENABLED(SMP)
static void dummy_pending_ipi_clear(ulong hart, ulong arg0, ulong arg1)
{
}
#endif
int arch_cpu_init_dm(void)
{
int ret;
@ -111,6 +122,15 @@ int arch_cpu_init_dm(void)
ret = riscv_init_ipi();
if (ret)
return ret;
/*
* Clear all pending IPIs on secondary harts. We don't do anything on
* the boot hart, since we never send an IPI to ourselves, and no
* interrupts are enabled
*/
ret = smp_call_function((ulong)dummy_pending_ipi_clear, 0, 0, 0);
if (ret)
return ret;
#endif
return 0;