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Subject: Re: [RFC PATCH v2 2/3] powernv/cpuidle: Pass pointers instead of
 values to stop loop
To:     Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Cc:     huntbag@linux.vnet.ibm.com, npiggin@gmail.com,
        benh@kernel.crashing.org, mpe@ellerman.id.au,
        ego@linux.vnet.ibm.com
References: <20181011132237.14604-1-akshay.adiga@linux.vnet.ibm.com>
 <20181011132237.14604-3-akshay.adiga@linux.vnet.ibm.com>
From:   Frank Rowand <frowand.list@gmail.com>
Message-ID: <38ed1a99-0916-e293-7564-268b49001de0@gmail.com>
Date:   Thu, 11 Oct 2018 12:56:01 -0700
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+ devicetree mail list

On 10/11/18 06:22, Akshay Adiga wrote:
> Passing pointer to the pnv_idle_state instead of psscr value and mask.
> This helps us to pass more information to the stop loop. This will help to
> figure out the method to enter/exit idle state.
> 
> Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
> 
> ---
> Changes from v1 :
>  - Code is rebased on Nick Piggin's v4 patch "powerpc/64s: reimplement book3s
>    idle code in C"
> 
>  arch/powerpc/include/asm/processor.h  |  5 ++-
>  arch/powerpc/platforms/powernv/idle.c | 47 ++++++++++-----------------
>  drivers/cpuidle/cpuidle-powernv.c     | 15 +++------
>  3 files changed, 24 insertions(+), 43 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index 936795acba48..822d3236ad7f 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -43,6 +43,7 @@
>  #include <asm/thread_info.h>
>  #include <asm/ptrace.h>
>  #include <asm/hw_breakpoint.h>
> +#include <asm/cpuidle.h>
>  
>  /* We do _not_ want to define new machine types at all, those must die
>   * in favor of using the device-tree
> @@ -518,9 +519,7 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
>  extern int powersave_nap;	/* set if nap mode can be used in idle loop */
>  
>  extern void power7_idle_type(unsigned long type);
> -extern void power9_idle_type(unsigned long stop_psscr_val,
> -			      unsigned long stop_psscr_mask);
> -
> +extern void power9_idle_type(struct pnv_idle_states_t *state);
>  extern void flush_instruction_cache(void);
>  extern void hard_reset_now(void);
>  extern void poweroff_now(void);
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index 755918402591..681a23a066bb 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -44,8 +44,7 @@ int nr_pnv_idle_states;
>   * The default stop state that will be used by ppc_md.power_save
>   * function on platforms that support stop instruction.
>   */
> -static u64 pnv_default_stop_val;
> -static u64 pnv_default_stop_mask;
> +struct pnv_idle_states_t *pnv_default_state;
>  static bool default_stop_found;
>  
>  /*
> @@ -72,9 +71,7 @@ const int nr_known_versions = 1;
>   * psscr value and mask of the deepest stop idle state.
>   * Used when a cpu is offlined.
>   */
> -static u64 pnv_deepest_stop_psscr_val;
> -static u64 pnv_deepest_stop_psscr_mask;
> -static u64 pnv_deepest_stop_flag;
> +static struct pnv_idle_states_t *pnv_deepest_state;
>  static bool deepest_stop_found;
>  
>  static unsigned long power7_offline_type;
> @@ -96,7 +93,7 @@ static int pnv_save_sprs_for_deep_states(void)
>  	uint64_t hid5_val	= mfspr(SPRN_HID5);
>  	uint64_t hmeer_val	= mfspr(SPRN_HMEER);
>  	uint64_t msr_val = MSR_IDLE;
> -	uint64_t psscr_val = pnv_deepest_stop_psscr_val;
> +	uint64_t psscr_val = pnv_deepest_state->psscr_val;
>  
>  	for_each_present_cpu(cpu) {
>  		uint64_t pir = get_hard_smp_processor_id(cpu);
> @@ -820,17 +817,15 @@ static unsigned long power9_offline_stop(unsigned long psscr)
>  	return srr1;
>  }
>  
> -static unsigned long __power9_idle_type(unsigned long stop_psscr_val,
> -				      unsigned long stop_psscr_mask)
> +static unsigned long __power9_idle_type(struct pnv_idle_states_t *state)
>  {
>  	unsigned long psscr;
>  	unsigned long srr1;
>  
>  	if (!prep_irq_for_idle_irqsoff())
>  		return 0;
> -
>  	psscr = mfspr(SPRN_PSSCR);
> -	psscr = (psscr & ~stop_psscr_mask) | stop_psscr_val;
> +	psscr = (psscr & ~state->psscr_mask) | state->psscr_val;
>  
>  	__ppc64_runlatch_off();
>  	srr1 = power9_idle_stop(psscr, true);
> @@ -841,12 +836,10 @@ static unsigned long __power9_idle_type(unsigned long stop_psscr_val,
>  	return srr1;
>  }
>  
> -void power9_idle_type(unsigned long stop_psscr_val,
> -				      unsigned long stop_psscr_mask)
> +void power9_idle_type(struct pnv_idle_states_t *state)
>  {
>  	unsigned long srr1;
> -
> -	srr1 = __power9_idle_type(stop_psscr_val, stop_psscr_mask);
> +	srr1 = __power9_idle_type(state);
>  	irq_set_pending_from_srr1(srr1);
>  }
>  
> @@ -855,7 +848,7 @@ void power9_idle_type(unsigned long stop_psscr_val,
>   */
>  void power9_idle(void)
>  {
> -	power9_idle_type(pnv_default_stop_val, pnv_default_stop_mask);
> +	power9_idle_type(pnv_default_state);
>  }
>  
>  #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> @@ -974,8 +967,8 @@ unsigned long pnv_cpu_offline(unsigned int cpu)
>  		unsigned long psscr;
>  
>  		psscr = mfspr(SPRN_PSSCR);
> -		psscr = (psscr & ~pnv_deepest_stop_psscr_mask) |
> -						pnv_deepest_stop_psscr_val;
> +		psscr = (psscr & ~pnv_deepest_state->psscr_mask) |
> +						pnv_deepest_state->psscr_val;
>  		srr1 = power9_offline_stop(psscr);
>  	} else if (cpu_has_feature(CPU_FTR_ARCH_206) && power7_offline_type) {
>  		srr1 = power7_offline();
> @@ -1123,16 +1116,13 @@ static void __init pnv_power9_idle_init(void)
>  
>  		if (max_residency_ns < state->residency_ns) {
>  			max_residency_ns = state->residency_ns;
> -			pnv_deepest_stop_psscr_val = state->psscr_val;
> -			pnv_deepest_stop_psscr_mask = state->psscr_mask;
> -			pnv_deepest_stop_flag = state->flags;
> +			pnv_deepest_state = state;
>  			deepest_stop_found = true;
>  		}
>  
>  		if (!default_stop_found &&
>  		    (state->flags & OPAL_PM_STOP_INST_FAST)) {
> -			pnv_default_stop_val = state->psscr_val;
> -			pnv_default_stop_mask = state->psscr_mask;
> +			pnv_default_state = state;
>  			default_stop_found = true;
>  			WARN_ON(state->flags & OPAL_PM_LOSE_FULL_CONTEXT);
>  		}
> @@ -1143,15 +1133,15 @@ static void __init pnv_power9_idle_init(void)
>  	} else {
>  		ppc_md.power_save = power9_idle;
>  		pr_info("cpuidle-powernv: Default stop: psscr = 0x%016llx,mask=0x%016llx\n",
> -			pnv_default_stop_val, pnv_default_stop_mask);
> +			pnv_default_state->psscr_val, pnv_default_state->psscr_mask);
>  	}
>  
>  	if (unlikely(!deepest_stop_found)) {
>  		pr_warn("cpuidle-powernv: No suitable stop state for CPU-Hotplug. Offlined CPUs will busy wait");
>  	} else {
>  		pr_info("cpuidle-powernv: Deepest stop: psscr = 0x%016llx,mask=0x%016llx\n",
> -			pnv_deepest_stop_psscr_val,
> -			pnv_deepest_stop_psscr_mask);
> +			pnv_deepest_state->psscr_val,
> +			pnv_deepest_state->psscr_mask);
>  	}
>  
>  	pr_info("cpuidle-powernv: First stop level that may lose SPRs = 0x%lld\n",
> @@ -1173,16 +1163,15 @@ static void __init pnv_disable_deep_states(void)
>  	pr_warn("cpuidle-powernv: Idle power-savings, CPU-Hotplug affected\n");
>  
>  	if (cpu_has_feature(CPU_FTR_ARCH_300) &&
> -	    (pnv_deepest_stop_flag & OPAL_PM_LOSE_FULL_CONTEXT)) {
> +	    (pnv_deepest_state->flags & OPAL_PM_LOSE_FULL_CONTEXT)) {
>  		/*
>  		 * Use the default stop state for CPU-Hotplug
>  		 * if available.
>  		 */
>  		if (default_stop_found) {
> -			pnv_deepest_stop_psscr_val = pnv_default_stop_val;
> -			pnv_deepest_stop_psscr_mask = pnv_default_stop_mask;
> +			pnv_deepest_state = pnv_default_state;
>  			pr_warn("cpuidle-powernv: Offlined CPUs will stop with psscr = 0x%016llx\n",
> -				pnv_deepest_stop_psscr_val);
> +				pnv_deepest_state->psscr_val);
>  		} else { /* Fallback to snooze loop for CPU-Hotplug */
>  			deepest_stop_found = false;
>  			pr_warn("cpuidle-powernv: Offlined CPUs will busy wait\n");
> diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
> index a15514ebd1c3..5116d5991d30 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -35,13 +35,7 @@ static struct cpuidle_driver powernv_idle_driver = {
>  static int max_idle_state __read_mostly;
>  static struct cpuidle_state *cpuidle_state_table __read_mostly;
>  
> -struct stop_psscr_table {
> -	u64 val;
> -	u64 mask;
> -};
> -
> -static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;
> -
> +struct pnv_idle_states_t idx_to_state_ptr[CPUIDLE_STATE_MAX] __read_mostly;
>  static u64 default_snooze_timeout __read_mostly;
>  static bool snooze_timeout_en __read_mostly;
>  
> @@ -143,8 +137,9 @@ static int stop_loop(struct cpuidle_device *dev,
>  		     struct cpuidle_driver *drv,
>  		     int index)
>  {
> -	power9_idle_type(stop_psscr_table[index].val,
> -			 stop_psscr_table[index].mask);
> +	struct pnv_idle_states_t *state;
> +	state = &pnv_idle_states[index];
> +	power9_idle_type(state);
>  	return index;
>  }
>  
> @@ -242,8 +237,6 @@ static inline void add_powernv_state(int index, const char *name,
>  	powernv_states[index].exit_latency = exit_latency;
>  	powernv_states[index].enter = idle_fn;
>  	/* For power8 and below psscr_* will be 0 */
> -	stop_psscr_table[index].val = psscr_val;
> -	stop_psscr_table[index].mask = psscr_mask;
>  }
>  
>  /*
>