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Message-ID: <175CCF5F49938B4D99B2E3EF7F558EBE5507A3B59B@SC-VEXCH4.marvell.com>
Date: Wed, 23 Apr 2014 03:31:09 -0700
From: Neil Zhang <zhangwm@...vell.com>
To: Will Deacon <will.deacon@....com>
CC: "linux@....linux.org.uk" <linux@....linux.org.uk>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Sudeep Holla <Sudeep.Holla@....com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v4] ARM: perf: save/restore pmu registers in pm notifier
> -----Original Message-----
> From: Will Deacon [mailto:will.deacon@....com]
> Sent: 2014年4月22日 18:37
> To: Neil Zhang
> Cc: linux@....linux.org.uk; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; Sudeep Holla; devicetree@...r.kernel.org
> Subject: Re: [PATCH v4] ARM: perf: save/restore pmu registers in pm notifier
>
> Hi Neil,
>
> On Tue, Apr 22, 2014 at 03:26:36AM +0100, Neil Zhang wrote:
> > This adds core support for saving and restoring CPU PMU registers for
> > suspend/resume support i.e. deeper C-states in cpuidle terms.
> > This patch adds support only to ARMv7 PMU registers save/restore.
> > It needs to be extended to xscale and ARMv6 if needed.
> >
> > I made this patch because DS-5 is not working on Marvell's CA7 based SoCs.
> > And it has consulted Sudeep KarkadaNagesha's patch set for multiple PMUs.
> >
> > Thanks Will and Sudeep's suggestion to only save / restore used events.
>
> Whilst this is a step in the right direction, I'd still like to see the save/restore
> predicated on something in the device-tree or otherwise. Most SoCs *don't*
> require these registers to be preserved by software, so we need a way to
> describe that the PMU is in a power-domain where its state is lost when the
> CPU goes idle.
>
> This doesn't sound like a PMU-specific problem, so there's a possibility that
> this has been discussed elsewhere, in the context of other IP blocks
>
> [adding the devicetree list in case somebody there is aware of any work in
> this area]
>
Thanks Will.
What should I do now?
Add a filed under PMU or waiting for somebody whether there are general supporting for power domain maintain.
> Will
>
> > diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
> > index ae1919b..3de3db7 100644
> > --- a/arch/arm/include/asm/pmu.h
> > +++ b/arch/arm/include/asm/pmu.h
> > @@ -83,6 +83,10 @@ struct arm_pmu {
> > int (*request_irq)(struct arm_pmu *, irq_handler_t handler);
> > void (*free_irq)(struct arm_pmu *);
> > int (*map_event)(struct perf_event *event);
> > + int (*register_pm_notifier)(struct arm_pmu *);
> > + void (*unregister_pm_notifier)(struct arm_pmu *);
> > + void (*save_regs)(struct arm_pmu *);
> > + void (*restore_regs)(struct arm_pmu *);
> > int num_events;
> > atomic_t active_events;
> > struct mutex reserve_mutex;
> > diff --git a/arch/arm/kernel/perf_event.c
> > b/arch/arm/kernel/perf_event.c index a6bc431..08822de 100644
> > --- a/arch/arm/kernel/perf_event.c
> > +++ b/arch/arm/kernel/perf_event.c
> > @@ -326,6 +326,7 @@ static void
> > armpmu_release_hardware(struct arm_pmu *armpmu) {
> > armpmu->free_irq(armpmu);
> > + armpmu->unregister_pm_notifier(armpmu);
> > pm_runtime_put_sync(&armpmu->plat_device->dev);
> > }
> >
> > @@ -339,6 +340,7 @@ armpmu_reserve_hardware(struct arm_pmu
> *armpmu)
> > return -ENODEV;
> >
> > pm_runtime_get_sync(&pmu_device->dev);
> > + armpmu->register_pm_notifier(armpmu);
> > err = armpmu->request_irq(armpmu, armpmu_dispatch_irq);
> > if (err) {
> > armpmu_release_hardware(armpmu);
> > diff --git a/arch/arm/kernel/perf_event_cpu.c
> > b/arch/arm/kernel/perf_event_cpu.c
> > index 51798d7..79e1c06 100644
> > --- a/arch/arm/kernel/perf_event_cpu.c
> > +++ b/arch/arm/kernel/perf_event_cpu.c
> > @@ -19,6 +19,7 @@
> > #define pr_fmt(fmt) "CPU PMU: " fmt
> >
> > #include <linux/bitmap.h>
> > +#include <linux/cpu_pm.h>
> > #include <linux/export.h>
> > #include <linux/kernel.h>
> > #include <linux/of.h>
> > @@ -173,6 +174,31 @@ static int cpu_pmu_request_irq(struct arm_pmu
> *cpu_pmu, irq_handler_t handler)
> > return 0;
> > }
> >
> > +static int cpu_pmu_pm_notify(struct notifier_block *b,
> > + unsigned long action, void *v)
> > +{
> > + if (action == CPU_PM_ENTER && cpu_pmu->save_regs)
> > + cpu_pmu->save_regs(cpu_pmu);
> > + else if (action == CPU_PM_EXIT && cpu_pmu->restore_regs)
> > + cpu_pmu->restore_regs(cpu_pmu);
> > +
> > + return NOTIFY_OK;
> > +}
> > +
> > +static struct notifier_block cpu_pmu_pm_notifier = {
> > + .notifier_call = cpu_pmu_pm_notify,
> > +};
> > +
> > +static int cpu_pmu_register_pm_notifier(struct arm_pmu *cpu_pmu) {
> > + return cpu_pm_register_notifier(&cpu_pmu_pm_notifier);
> > +}
> > +
> > +static void cpu_pmu_unregister_pm_notifier(struct arm_pmu *cpu_pmu) {
> > + cpu_pm_unregister_notifier(&cpu_pmu_pm_notifier);
> > +}
> > +
> > static void cpu_pmu_init(struct arm_pmu *cpu_pmu) {
> > int cpu;
> > @@ -187,6 +213,8 @@ static void cpu_pmu_init(struct arm_pmu
> *cpu_pmu)
> > cpu_pmu->get_hw_events = cpu_pmu_get_cpu_events;
> > cpu_pmu->request_irq = cpu_pmu_request_irq;
> > cpu_pmu->free_irq = cpu_pmu_free_irq;
> > + cpu_pmu->register_pm_notifier = cpu_pmu_register_pm_notifier;
> > + cpu_pmu->unregister_pm_notifier =
> cpu_pmu_unregister_pm_notifier;
> >
> > /* Ensure the PMU has sane values out of reset. */
> > if (cpu_pmu->reset)
> > diff --git a/arch/arm/kernel/perf_event_v7.c
> > b/arch/arm/kernel/perf_event_v7.c index f4ef398..9069310 100644
> > --- a/arch/arm/kernel/perf_event_v7.c
> > +++ b/arch/arm/kernel/perf_event_v7.c
> > @@ -1237,6 +1237,78 @@ static void armv7_pmnc_dump_regs(struct
> arm_pmu
> > *cpu_pmu) } #endif
> >
> > +struct armv7_pmuregs {
> > + u32 pmc;
> > + u32 pmcntenset;
> > + u32 pmintenset;
> > + u32 pmxevttype[8];
> > + u32 pmxevtcnt[8];
> > +};
> > +
> > +static DEFINE_PER_CPU(struct armv7_pmuregs, pmu_regs);
> > +
> > +static void armv7pmu_reset(void *info);
> > +
> > +static void armv7pmu_save_regs(struct arm_pmu *cpu_pmu) {
> > + struct pmu_hw_events *events = cpu_pmu->get_hw_events();
> > + struct armv7_pmuregs *regs;
> > + int bit;
> > +
> > + /* Check whether there are events used */
> > + bit = find_first_bit(events->used_mask, cpu_pmu->num_events);
> > + if (bit >= cpu_pmu->num_events)
> > + return;
> > +
> > + regs = this_cpu_ptr(&pmu_regs);
> > + for_each_set_bit(bit, events->used_mask, cpu_pmu->num_events) {
> > + if (bit) {
> > + armv7_pmnc_select_counter(bit);
> > + asm volatile("mrc p15, 0, %0, c9, c13, 1"
> > + : "=r"(regs->pmxevttype[bit]));
> > + asm volatile("mrc p15, 0, %0, c9, c13, 2"
> > + : "=r"(regs->pmxevtcnt[bit]));
> > + } else
> > + asm volatile("mrc p15, 0, %0, c9, c13, 0"
> > + : "=r" (regs->pmxevtcnt[0]));
> > + }
> > +
> > + asm volatile("mrc p15, 0, %0, c9, c12, 1" : "=r" (regs->pmcntenset));
> > + asm volatile("mrc p15, 0, %0, c9, c14, 1" : "=r" (regs->pmintenset));
> > + asm volatile("mrc p15, 0, %0, c9, c12, 0" : "=r" (regs->pmc)); }
> > +
> > +static void armv7pmu_restore_regs(struct arm_pmu *cpu_pmu) {
> > + struct pmu_hw_events *events = cpu_pmu->get_hw_events();
> > + struct armv7_pmuregs *regs;
> > + int bit;
> > +
> > + /* Check whether there are events used */
> > + bit = find_first_bit(events->used_mask, cpu_pmu->num_events);
> > + if (bit >= cpu_pmu->num_events)
> > + return;
> > +
> > + armv7pmu_reset(cpu_pmu);
> > +
> > + regs = this_cpu_ptr(&pmu_regs);
> > + for_each_set_bit(bit, events->used_mask, cpu_pmu->num_events) {
> > + if (bit) {
> > + armv7_pmnc_select_counter(bit);
> > + asm volatile("mcr p15, 0, %0, c9, c13, 1"
> > + : : "r"(regs->pmxevttype[bit]));
> > + asm volatile("mcr p15, 0, %0, c9, c13, 2"
> > + : : "r"(regs->pmxevtcnt[bit]));
> > + } else
> > + asm volatile("mcr p15, 0, %0, c9, c13, 0"
> > + : : "r" (regs->pmxevtcnt[0]));
> > + }
> > +
> > + asm volatile("mcr p15, 0, %0, c9, c12, 1" : : "r" (regs->pmcntenset));
> > + asm volatile("mcr p15, 0, %0, c9, c14, 1" : : "r" (regs->pmintenset));
> > + asm volatile("mcr p15, 0, %0, c9, c12, 0" : : "r" (regs->pmc)); }
> > +
> > static void armv7pmu_enable_event(struct perf_event *event) {
> > unsigned long flags;
> > @@ -1528,6 +1600,8 @@ static void armv7pmu_init(struct arm_pmu
> *cpu_pmu)
> > cpu_pmu->start = armv7pmu_start;
> > cpu_pmu->stop = armv7pmu_stop;
> > cpu_pmu->reset = armv7pmu_reset;
> > + cpu_pmu->save_regs = armv7pmu_save_regs;
> > + cpu_pmu->restore_regs = armv7pmu_restore_regs;
> > cpu_pmu->max_period = (1LLU << 32) - 1;
> > };
> >
> > --
> > 1.7.9.5
> >
> >
Best Regards,
Neil Zhang
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