linux-kernel - RE: [PATCH v3 1/4] perf: arm_cspmu: Split 64-bit write to 32-bit writes

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Message-ID: <903ad734-461-c181-9633-3ff29715cc0@os.amperecomputing.com>
Date:   Wed, 21 Jun 2023 12:05:26 -0700 (PDT)
From:   Ilkka Koskinen <ilkka@...amperecomputing.com>
To:     Besar Wicaksono <bwicaksono@...dia.com>
cc:     Ilkka Koskinen <ilkka@...amperecomputing.com>,
        Jonathan Corbet <corbet@....net>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Robin Murphy <robin.murphy@....com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v3 1/4] perf: arm_cspmu: Split 64-bit write to 32-bit
 writes


Hi Besar,

On Tue, 20 Jun 2023, Besar Wicaksono wrote:
>> -----Original Message-----
>> From: Ilkka Koskinen <ilkka@...amperecomputing.com>
>> Sent: Wednesday, June 7, 2023 3:32 PM
>> To: Jonathan Corbet <corbet@....net>; Will Deacon <will@...nel.org>; Mark
>> Rutland <mark.rutland@....com>; Besar Wicaksono
>> <bwicaksono@...dia.com>; Suzuki K Poulose <suzuki.poulose@....com>;
>> Robin Murphy <robin.murphy@....com>
>> Cc: linux-doc@...r.kernel.org; linux-kernel@...r.kernel.org; linux-arm-
>> kernel@...ts.infradead.org; Ilkka Koskinen <ilkka@...amperecomputing.com>
>> Subject: [PATCH v3 1/4] perf: arm_cspmu: Split 64-bit write to 32-bit writes
>>
>> External email: Use caution opening links or attachments
>>
>>
>> Split the 64-bit register accesses if 64-bit access is not supported
>> by the PMU.
>>
>> Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
>> ---
>>  drivers/perf/arm_cspmu/arm_cspmu.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c
>> b/drivers/perf/arm_cspmu/arm_cspmu.c
>> index a3f1c410b417..f8b4a149eb88 100644
>> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
>> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
>> @@ -702,7 +702,10 @@ static void arm_cspmu_write_counter(struct
>> perf_event *event, u64 val)
>>         if (use_64b_counter_reg(cspmu)) {
>>                 offset = counter_offset(sizeof(u64), event->hw.idx);
>>
>> -               writeq(val, cspmu->base1 + offset);
>> +               if (supports_64bit_atomics(cspmu))
>
> Looks good to me, but this function was recently replaced by
> arm_cspmu::has_atomic_dword. Please rebase the patch.

Sure, I do that.

Cheers, Ilkka

>
> Thanks,
> Besar
>
>> +                       writeq(val, cspmu->base1 + offset);
>> +               else
>> +                       lo_hi_writeq(val, cspmu->base1 + offset);
>>         } else {
>>                 offset = counter_offset(sizeof(u32), event->hw.idx);
>>
>> --
>> 2.40.1
>
>