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SubjectRe: [RFC PATCH] Add IPI entry for CPU UP
On Mon, Jan 11, 2016 at 03:10:40PM +0800, Zhaoyang Huang wrote:
> In some ARM SOCs, IPI interrupt is used for hotplug in one cpu, that is,
> sending a IPI to the core in WFI and powerdown status. So Add a IPI
> entry for handle this kind of cpu up interrupt

On arm64 SOCs, with a mainline kernel, you can only hotplug CPUs out
and back in by using the PSCI firmware interface, which does not
require an IPI to boot a CPU, therefore this patch is useless.

Lorenzo

> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@spreadtrum.com>
> ---
> arch/arm64/kernel/smp.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index b1adc51..20e63c9 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -70,6 +70,7 @@ enum ipi_msg_type {
> IPI_CPU_STOP,
> IPI_TIMER,
> IPI_IRQ_WORK,
> + IPI_CPU_UP,
> };
>
> /*
> @@ -627,6 +628,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = {
> S(IPI_CPU_STOP, "CPU stop interrupts"),
> S(IPI_TIMER, "Timer broadcast interrupts"),
> S(IPI_IRQ_WORK, "IRQ work interrupts"),
> + S(IPI_CPU_UP, "Hotplug cpu up by ipi"),
> };
>
> static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
> @@ -746,6 +748,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
> irq_exit();
> break;
> #endif
> + case IPI_CPU_UP:
> + break;
>
> default:
> pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
> @@ -798,3 +802,9 @@ int setup_profiling_timer(unsigned int multiplier)
> {
> return -EINVAL;
> }
> +
> +void smp_send_cpuup(int cpu)
> +{
> + smp_cross_call(cpumask_of(cpu), IPI_CPU_UP);
> +}
> +
> --
> 1.7.9.5
>

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