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SubjectRe: [PATCH] ARM: bcm2836: Send event when onlining other cores
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On 08/08/2017 04:04 AM, Phil Elwell wrote:
> Secondary cores should enter a low-power idle state when waiting to
> be started. The "wfe" instruction causes a core to wait until an event
> or interrupt arrives before continuing to the next instruction, and
> the "sev" instruction sends a wakeup event to the other cores.
>
> Add an "sev" (and a memory barrier) to bcm2836_boot_secondary, the
> function that wakes the waiting cores during booting. This is required
> if the secondary cores are sitting in "wfe", and harmless if not.

Eric, should I just pick this up for the upcoming ARM SoC pull requests
that I am preparing, or do you have more changes aside from the two tags
I already merged?

Thanks!

>
> Signed-off-by: Phil Elwell <phil@raspberrypi.org>
> ---
> arch/arm/mach-bcm/platsmp.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm/mach-bcm/platsmp.c b/arch/arm/mach-bcm/platsmp.c
> index 3fa1a99..7811160 100644
> --- a/arch/arm/mach-bcm/platsmp.c
> +++ b/arch/arm/mach-bcm/platsmp.c
> @@ -312,6 +312,9 @@ static int bcm2836_boot_secondary(unsigned int cpu, struct task_struct *idle)
> writel(virt_to_phys(secondary_startup),
> intc_base + LOCAL_MAILBOX3_SET0 + 16 * cpu);
>
> + dsb(sy);
> + sev();
> +
> iounmap(intc_base);
>
> return 0;
>

--
Florian

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