linux-kernel - Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations

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Date:	Fri, 31 Jul 2015 18:59:38 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	<b29983@...escale.com>
CC:	<b07421@...escale.com>, <linux-kernel@...r.kernel.org>,
	Tang Yuantian <Yuantian.Tang@...escale.com>,
	Chenhui Zhao <chenhui.zhao@...escale.com>,
	Tang Yuantian <Yuantian.Tang@...scale.com>
Subject: Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations

On Fri, 2015-07-31 at 17:20 +0800, b29983@...escale.com wrote:
> @@ -71,7 +56,7 @@ static void mpc85xx_give_timebase(void)
>               barrier();
>       tb_req = 0;
>  
> -     mpc85xx_timebase_freeze(1);
> +     qoriq_pm_ops->freeze_time_base(1);

freeze_time_base() takes a bool.  Use true/false.

>  #ifdef CONFIG_PPC64
>       /*
>        * e5500/e6500 have a workaround for erratum A-006958 in place
> @@ -104,7 +89,7 @@ static void mpc85xx_give_timebase(void)
>       while (tb_valid)
>               barrier();
>  
> -     mpc85xx_timebase_freeze(0);
> +     qoriq_pm_ops->freeze_time_base(0);
>  
>       local_irq_restore(flags);
>  }
> @@ -127,20 +112,10 @@ static void mpc85xx_take_timebase(void)
>  }
>  
>  #ifdef CONFIG_HOTPLUG_CPU
> -static void smp_85xx_mach_cpu_die(void)
> +static void e500_cpu_idle(void)

This is not the function that gets called during normal cpu idle, and it 
shouldn't be named to look like it is.

>  {
> -     unsigned int cpu = smp_processor_id();
>       u32 tmp;
>  
> -     local_irq_disable();
> -     idle_task_exit();
> -     generic_set_cpu_dead(cpu);
> -     mb();
> -
> -     mtspr(SPRN_TCR, 0);
> -
> -     cur_cpu_spec->cpu_down_flush();
> -
>       tmp = (mfspr(SPRN_HID0) & ~(HID0_DOZE|HID0_SLEEP)) | HID0_NAP;
>       mtspr(SPRN_HID0, tmp);
>       isync();
> @@ -151,6 +126,25 @@ static void smp_85xx_mach_cpu_die(void)
>       mb();
>       mtmsr(tmp);
>       isync();
> +}
> +
> +static void qoriq_cpu_dying(void)
> +{
> +     unsigned int cpu = smp_processor_id();
> +
> +     hard_irq_disable();
> +     /* mask all irqs to prevent cpu wakeup */
> +     qoriq_pm_ops->irq_mask(cpu);
> +     idle_task_exit();
> +
> +     mtspr(SPRN_TCR, 0);
> +     mtspr(SPRN_TSR, mfspr(SPRN_TSR));
> +
> +     cur_cpu_spec->cpu_down_flush();
> +
> +     generic_set_cpu_dead(cpu);
> +
> +     e500_cpu_idle();

Why is something that claims to be applicable to all qoriq directly calling 
an e500v2-specific function?

Could you explain irq_mask()?  Why would there still be IRQs destined for 
this CPU at this point?

@@ -431,21 +415,9 @@ void __init mpc85xx_smp_init(void)
>               smp_85xx_ops.probe = NULL;
>       }
>  
> -     np = of_find_matching_node(NULL, mpc85xx_smp_guts_ids);
> -     if (np) {
> -             guts = of_iomap(np, 0);
> -             of_node_put(np);
> -             if (!guts) {
> -                     pr_err("%s: Could not map guts node address\n",
> -                                                             __func__);
> -                     return;
> -             }
> -             smp_85xx_ops.give_timebase = mpc85xx_give_timebase;
> -             smp_85xx_ops.take_timebase = mpc85xx_take_timebase;
>  #ifdef CONFIG_HOTPLUG_CPU
> -             ppc_md.cpu_die = smp_85xx_mach_cpu_die;
> +     ppc_md.cpu_die = qoriq_cpu_dying;
>  #endif

Shouldn't you make sure there's a valid qoriq_pm_ops before setting 
cpu_die()?  Or make sure that qoriq_cpu_dying() works regardless.

-Scott

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