2019-01-18 05:46:56

by Pramod Kumar

[permalink] [raw]
Subject: [PATCH INTERNAL RFC 1/1] arm64: Use PSCI calls for CPU stop when hotplug is supported

If CPU hotplug is supported, ipi_cpu_stop should use PSCI cpudie
call to stop the CPU. This call ensures L1/L2 cache flush,
CPUs cache-cohenrecy setting w.r.to interconnect.

Apart from this, this gives control to f/w to reduce power consumption
by take appropriate decesion on power rails for plugging-out core.

Signed-off-by: Pramod Kumar <[email protected]>
Reviewed-by: Ray Jui <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
---
arch/arm64/kernel/smp.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 1598d6f..360e52b 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -822,8 +822,13 @@ static void ipi_cpu_stop(unsigned int cpu)
local_daif_mask();
sdei_mask_local_cpu();

+#ifdef CONFIG_HOTPLUG_CPU
+ if (cpu_ops[cpu]->cpu_die)
+ cpu_ops[cpu]->cpu_die(cpu);
+#else
while (1)
cpu_relax();
+#endif
}

#ifdef CONFIG_KEXEC_CORE
--
1.9.1