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Message-ID: <25c378d3-8914-4f24-8ea9-0e2204c90727@ghiti.fr>
Date:   Thu, 15 Jun 2023 09:16:51 +0200
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Subject: Re: [PATCH v2 03/10] riscv: Make legacy counter enum match the HW
 numbering
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To:     Andrew Jones <ajones@ventanamicro.com>,
        Alexandre Ghiti <alexghiti@rivosinc.com>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Atish Patra <atishp@atishpatra.org>,
        Anup Patel <anup@brainfault.org>,
        Will Deacon <will@kernel.org>, Rob Herring <robh@kernel.org>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org, linux-riscv@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
References: <20230512085321.13259-1-alexghiti@rivosinc.com>
 <20230512085321.13259-4-alexghiti@rivosinc.com>
 <20230531-ddb2d631e152526102f41d5e@orel>
From:   Alexandre Ghiti <alex@ghiti.fr>
In-Reply-To: <20230531-ddb2d631e152526102f41d5e@orel>
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On 31/05/2023 16:01, Andrew Jones wrote:
> On Fri, May 12, 2023 at 10:53:14AM +0200, Alexandre Ghiti wrote:
>> RISCV_PMU_LEGACY_INSTRET used to be set to 1 whereas the offset of this
>> hardware counter from CSR_CYCLE is actually 2: make this offset match the
>> real hw offset so that we can directly expose those values to userspace.
>>
>> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
>> ---
>>   drivers/perf/riscv_pmu_legacy.c | 7 +++++--
>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/perf/riscv_pmu_legacy.c b/drivers/perf/riscv_pmu_legacy.c
>> index ca9e20bfc7ac..0d8c9d8849ee 100644
>> --- a/drivers/perf/riscv_pmu_legacy.c
>> +++ b/drivers/perf/riscv_pmu_legacy.c
>> @@ -12,8 +12,11 @@
>>   #include <linux/perf/riscv_pmu.h>
>>   #include <linux/platform_device.h>
>>   
>> -#define RISCV_PMU_LEGACY_CYCLE		0
>> -#define RISCV_PMU_LEGACY_INSTRET	1
>> +enum {
>> +	RISCV_PMU_LEGACY_CYCLE,
>> +	RISCV_PMU_LEGACY_TIME,
>> +	RISCV_PMU_LEGACY_INSTRET
>> +};
> I guess this doesn't hurt, since these are just indices internal to this
> driver, but it's a bit odd to also have a RISCV_PMU_LEGACY_TIME, when
> the driver is only for cycle and instret, as its Kconfig help text says.


I understand and you're right, that's weird, so I'll change that with 
the following:

diff --git a/drivers/perf/riscv_pmu_legacy.c 
b/drivers/perf/riscv_pmu_legacy.c
index ca9e20bfc7ac..6a000abc28bb 100644
--- a/drivers/perf/riscv_pmu_legacy.c
+++ b/drivers/perf/riscv_pmu_legacy.c
@@ -13,7 +13,7 @@
  #include <linux/platform_device.h>

  #define RISCV_PMU_LEGACY_CYCLE         0
-#define RISCV_PMU_LEGACY_INSTRET       1
+#define RISCV_PMU_LEGACY_INSTRET       2

  static bool pmu_init_done;

Thanks!


> Thanks,
> drew
>
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