Am Freitag, 25. März 2022, 15:38:32 CET schrieb Helge Deller:
> Let the PDC firmware put the CPU into firmware idle loop with
> pdc_cpu_rendezvous() function.
>
> Signed-off-by: Helge Deller <deller@xxxxxx>
> ---
> arch/parisc/kernel/process.c | 33 ++++++++++++++++++++++++++++++---
> 1 file changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
> index ea3d83b6fb62..44fa89fbb280 100644
> --- a/arch/parisc/kernel/process.c
> +++ b/arch/parisc/kernel/process.c
> @@ -38,6 +38,7 @@
> #include <linux/rcupdate.h>
> #include <linux/random.h>
> #include <linux/nmi.h>
> +#include <linux/sched/hotplug.h>
>
> #include <asm/io.h>
> #include <asm/asm-offsets.h>
> @@ -46,6 +47,7 @@
> #include <asm/pdc_chassis.h>
> #include <asm/unwind.h>
> #include <asm/sections.h>
> +#include <asm/cacheflush.h>
>
> #define COMMAND_GLOBAL F_EXTEND(0xfffe0030)
> #define CMD_RESET 5 /* reset any module */
> @@ -158,10 +160,35 @@ void release_thread(struct task_struct *dead_task)
> int running_on_qemu __ro_after_init;
> EXPORT_SYMBOL(running_on_qemu);
>
> -void __cpuidle arch_cpu_idle_dead(void)
> +/*
> + * Called from the idle thread for the CPU which has been shutdown.
> + */
> +void arch_cpu_idle_dead(void)
> {
> - /* nop on real hardware, qemu will offline CPU. */
> - asm volatile("or %%r31,%%r31,%%r31\n":::);
> +#ifdef CONFIG_HOTPLUG_CPU
> + idle_task_exit();
> +
> + local_irq_disable();
> +
> + /*
> + * Tell __cpu_die() that this CPU is now safe to dispose of.
> + */
> + (void)cpu_report_death();
> +
> + /*
> + * Ensure that the cache lines are written out.
> + */
> + flush_cache_all_local();
> + flush_tlb_all_local(NULL);
> +
> + /*
> + * Let PDC firmware put CPU into firmware idle loop.
> + */
> + __pdc_cpu_rendezvous();
That could all be one-line comments for a higher code/line ratio ;)Attachment:
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