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Subject: Re: [PATCH v3 2/3] powerpc/powernv/idle: Rename
 pnv_first_spr_loss_level variable
To:     Nicholas Piggin <npiggin@gmail.com>, benh@kernel.crashing.org,
        ego@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, mikey@neuling.org,
        mpe@ellerman.id.au, paulus@samba.org, pratik.r.sampat@gmail.com,
        svaidy@linux.ibm.com
References: <20200717185306.60607-1-psampat@linux.ibm.com>
 <20200717185306.60607-3-psampat@linux.ibm.com>
 <1595202681.bt4670u7q7.astroid@bobo.none>
From:   Pratik Sampat <psampat@linux.ibm.com>
Message-ID: <81dcf34e-870d-b3a1-7876-a6a2f0b37d1f@linux.ibm.com>
Date:   Tue, 21 Jul 2020 15:59:10 +0530
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On 20/07/20 5:27 am, Nicholas Piggin wrote:
> Excerpts from Pratik Rajesh Sampat's message of July 18, 2020 4:53 am:
>> Replace the variable name from using "pnv_first_spr_loss_level" to
>> "pnv_first_fullstate_loss_level".
>>
>> As pnv_first_spr_loss_level is supposed to be the earliest state that
>> has OPAL_PM_LOSE_FULL_CONTEXT set, however as shallow states too loose
>> SPR values, render an incorrect terminology.
> It also doesn't lose "full" state at this loss level though. From the
> architecture it could be called "hv state loss level", but in POWER10
> even that is not strictly true.
>
Right. Just discovered that deep stop states won't loose full state
P10 onwards.
Would it better if we rename it as "pnv_all_spr_loss_state" instead
so that it stays generic enough while being semantically coherent?

Thanks
Pratik

>> Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>
>> ---
>>   arch/powerpc/platforms/powernv/idle.c | 18 +++++++++---------
>>   1 file changed, 9 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
>> index f62904f70fc6..d439e11af101 100644
>> --- a/arch/powerpc/platforms/powernv/idle.c
>> +++ b/arch/powerpc/platforms/powernv/idle.c
>> @@ -48,7 +48,7 @@ static bool default_stop_found;
>>    * First stop state levels when SPR and TB loss can occur.
>>    */
>>   static u64 pnv_first_tb_loss_level = MAX_STOP_STATE + 1;
>> -static u64 pnv_first_spr_loss_level = MAX_STOP_STATE + 1;
>> +static u64 pnv_first_fullstate_loss_level = MAX_STOP_STATE + 1;
>>   
>>   /*
>>    * psscr value and mask of the deepest stop idle state.
>> @@ -657,7 +657,7 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
>>   		  */
>>   		mmcr0		= mfspr(SPRN_MMCR0);
>>   	}
>> -	if ((psscr & PSSCR_RL_MASK) >= pnv_first_spr_loss_level) {
>> +	if ((psscr & PSSCR_RL_MASK) >= pnv_first_fullstate_loss_level) {
>>   		sprs.lpcr	= mfspr(SPRN_LPCR);
>>   		sprs.hfscr	= mfspr(SPRN_HFSCR);
>>   		sprs.fscr	= mfspr(SPRN_FSCR);
>> @@ -741,7 +741,7 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
>>   	 * just always test PSSCR for SPR/TB state loss.
>>   	 */
>>   	pls = (psscr & PSSCR_PLS) >> PSSCR_PLS_SHIFT;
>> -	if (likely(pls < pnv_first_spr_loss_level)) {
>> +	if (likely(pls < pnv_first_fullstate_loss_level)) {
>>   		if (sprs_saved)
>>   			atomic_stop_thread_idle();
>>   		goto out;
>> @@ -1088,7 +1088,7 @@ static void __init pnv_power9_idle_init(void)
>>   	 * the deepest loss-less (OPAL_PM_STOP_INST_FAST) stop state.
>>   	 */
>>   	pnv_first_tb_loss_level = MAX_STOP_STATE + 1;
>> -	pnv_first_spr_loss_level = MAX_STOP_STATE + 1;
>> +	pnv_first_fullstate_loss_level = MAX_STOP_STATE + 1;
>>   	for (i = 0; i < nr_pnv_idle_states; i++) {
>>   		int err;
>>   		struct pnv_idle_states_t *state = &pnv_idle_states[i];
>> @@ -1099,8 +1099,8 @@ static void __init pnv_power9_idle_init(void)
>>   			pnv_first_tb_loss_level = psscr_rl;
>>   
>>   		if ((state->flags & OPAL_PM_LOSE_FULL_CONTEXT) &&
>> -		     (pnv_first_spr_loss_level > psscr_rl))
>> -			pnv_first_spr_loss_level = psscr_rl;
>> +		     (pnv_first_fullstate_loss_level > psscr_rl))
>> +			pnv_first_fullstate_loss_level = psscr_rl;
>>   
>>   		/*
>>   		 * The idle code does not deal with TB loss occurring
>> @@ -1111,8 +1111,8 @@ static void __init pnv_power9_idle_init(void)
>>   		 * compatibility.
>>   		 */
>>   		if ((state->flags & OPAL_PM_TIMEBASE_STOP) &&
>> -		     (pnv_first_spr_loss_level > psscr_rl))
>> -			pnv_first_spr_loss_level = psscr_rl;
>> +		     (pnv_first_fullstate_loss_level > psscr_rl))
>> +			pnv_first_fullstate_loss_level = psscr_rl;
>>   
>>   		err = validate_psscr_val_mask(&state->psscr_val,
>>   					      &state->psscr_mask,
>> @@ -1158,7 +1158,7 @@ static void __init pnv_power9_idle_init(void)
>>   	}
>>   
>>   	pr_info("cpuidle-powernv: First stop level that may lose SPRs = 0x%llx\n",
>> -		pnv_first_spr_loss_level);
>> +		pnv_first_fullstate_loss_level);
>>   
>>   	pr_info("cpuidle-powernv: First stop level that may lose timebase = 0x%llx\n",
>>   		pnv_first_tb_loss_level);
>> -- 
>> 2.25.4
>>
>>