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Message-ID: <54479472.9060004@cn.fujitsu.com>
Date: Wed, 22 Oct 2014 19:26:42 +0800
From: Chai Wen <chaiw.fnst@...fujitsu.com>
To: Mark Rutland <mark.rutland@....com>
CC: Will Deacon <Will.Deacon@....com>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"yuichi.kusakabe@...fujitsu.com" <yuichi.kusakabe@...fujitsu.com>,
Sudeep Holla <Sudeep.Holla@....com>
Subject: Re: [PATCH 1/2] ARM: perf: armv7 remove useless return and check
of idx in counter handling
On 10/22/2014 06:47 PM, Mark Rutland wrote:
> Hi,
>
> On Wed, Oct 22, 2014 at 09:21:46AM +0100, chai wen wrote:
>> Idx sanity check was once implemented separately in these counter handling
>> functions and then return value was treated as a judgement.
>> armv7_pmnc_select_counter()
>> armv7_pmnc_enable_counter()
>> armv7_pmnc_disable_counter()
>> armv7_pmnc_enable_intens()
>> armv7_pmnc_disable_intens()
>> But we do not need to do this now, and the return of idx is useless.
>>
>> Signed-off-by: chai wen <chaiw.fnst@...fujitsu.com>
>
> It looks like the validation was moved out of all of these functions in
> 7279adbd9bb8ef8f (ARM: perf: check ARMv7 counter validity on a per-pmu
> basis), and we just missed the opportunity to simplify callers at the
> time.
>
> It would be nice if we mentioned that in the commit message -- it takes
> a while to figure out and it's handy for reference.
>
Yeah, sorry for forgetting to point out that.
>> ---
>> arch/arm/kernel/perf_event_v7.c | 32 ++++++++++++++------------------
>> 1 files changed, 14 insertions(+), 18 deletions(-)
>>
>> diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
>> index 116758b..f66a9b8 100644
>> --- a/arch/arm/kernel/perf_event_v7.c
>> +++ b/arch/arm/kernel/perf_event_v7.c
>> @@ -564,13 +564,11 @@ static inline int armv7_pmnc_counter_has_overflowed(u32 pmnc, int idx)
>> return pmnc & BIT(ARMV7_IDX_TO_COUNTER(idx));
>> }
>>
>> -static inline int armv7_pmnc_select_counter(int idx)
>> +static inline void armv7_pmnc_select_counter(int idx)
>> {
>> u32 counter = ARMV7_IDX_TO_COUNTER(idx);
>> asm volatile("mcr p15, 0, %0, c9, c12, 5" : : "r" (counter));
>> isb();
>> -
>> - return idx;
>> }
>>
>> static inline u32 armv7pmu_read_counter(struct perf_event *event)
>> @@ -585,8 +583,10 @@ static inline u32 armv7pmu_read_counter(struct perf_event *event)
>> smp_processor_id(), idx);
>> else if (idx == ARMV7_IDX_CYCLE_COUNTER)
>> asm volatile("mrc p15, 0, %0, c9, c13, 0" : "=r" (value));
>> - else if (armv7_pmnc_select_counter(idx) == idx)
>> + else {
>> + armv7_pmnc_select_counter(idx);
>> asm volatile("mrc p15, 0, %0, c9, c13, 2" : "=r" (value));
>> + }
>
> Please make the braces consistent -- if one branch in an if .. else
> chain needs them, they all do (see Documentation/CodingStyle).
>
>>
>> return value;
>> }
>> @@ -602,40 +602,38 @@ static inline void armv7pmu_write_counter(struct perf_event *event, u32 value)
>> smp_processor_id(), idx);
>> else if (idx == ARMV7_IDX_CYCLE_COUNTER)
>> asm volatile("mcr p15, 0, %0, c9, c13, 0" : : "r" (value));
>> - else if (armv7_pmnc_select_counter(idx) == idx)
>> + else {
>> + armv7_pmnc_select_counter(idx);
>> asm volatile("mcr p15, 0, %0, c9, c13, 2" : : "r" (value));
>> + }
>
> Likewise here.
>
> Otherwise this looks like a nice cleanup to me, so with those changes:
>
> Acked-by: Mark Rutland <mark.rutland@....com>
Thanks for your review. I'll send a update version later.
thanks
chai wen
>
> Thanks,
> Mark.
>
>> }
>>
>> static inline void armv7_pmnc_write_evtsel(int idx, u32 val)
>> {
>> - if (armv7_pmnc_select_counter(idx) == idx) {
>> - val &= ARMV7_EVTYPE_MASK;
>> - asm volatile("mcr p15, 0, %0, c9, c13, 1" : : "r" (val));
>> - }
>> + armv7_pmnc_select_counter(idx);
>> + val &= ARMV7_EVTYPE_MASK;
>> + asm volatile("mcr p15, 0, %0, c9, c13, 1" : : "r" (val));
>> }
>>
>> -static inline int armv7_pmnc_enable_counter(int idx)
>> +static inline void armv7_pmnc_enable_counter(int idx)
>> {
>> u32 counter = ARMV7_IDX_TO_COUNTER(idx);
>> asm volatile("mcr p15, 0, %0, c9, c12, 1" : : "r" (BIT(counter)));
>> - return idx;
>> }
>>
>> -static inline int armv7_pmnc_disable_counter(int idx)
>> +static inline void armv7_pmnc_disable_counter(int idx)
>> {
>> u32 counter = ARMV7_IDX_TO_COUNTER(idx);
>> asm volatile("mcr p15, 0, %0, c9, c12, 2" : : "r" (BIT(counter)));
>> - return idx;
>> }
>>
>> -static inline int armv7_pmnc_enable_intens(int idx)
>> +static inline void armv7_pmnc_enable_intens(int idx)
>> {
>> u32 counter = ARMV7_IDX_TO_COUNTER(idx);
>> asm volatile("mcr p15, 0, %0, c9, c14, 1" : : "r" (BIT(counter)));
>> - return idx;
>> }
>>
>> -static inline int armv7_pmnc_disable_intens(int idx)
>> +static inline void armv7_pmnc_disable_intens(int idx)
>> {
>> u32 counter = ARMV7_IDX_TO_COUNTER(idx);
>> asm volatile("mcr p15, 0, %0, c9, c14, 2" : : "r" (BIT(counter)));
>> @@ -643,8 +641,6 @@ static inline int armv7_pmnc_disable_intens(int idx)
>> /* Clear the overflow flag in case an interrupt is pending. */
>> asm volatile("mcr p15, 0, %0, c9, c12, 3" : : "r" (BIT(counter)));
>> isb();
>> -
>> - return idx;
>> }
>>
>> static inline u32 armv7_pmnc_getreset_flags(void)
>> --
>> 1.7.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
> .
>
--
Regards
Chai Wen
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