linux-kernel - Re: [PATCH v3 2/3] perf: add arm64 smmuv3 pmu driver

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Message-ID: <6d51a825-325f-5f78-20da-bf27f208fe37@arm.com>
Date:   Wed, 3 Oct 2018 10:46:57 +0100
From:   Jean-Philippe Brucker <jean-philippe.brucker@....com>
To:     Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "robin.murphy@....com" <robin.murphy@....com>
Cc:     "mark.rutland@....com" <mark.rutland@....com>,
        "vkilari@...eaurora.org" <vkilari@...eaurora.org>,
        "neil.m.leeder@...il.com" <neil.m.leeder@...il.com>,
        "pabba@...eaurora.org" <pabba@...eaurora.org>,
        John Garry <john.garry@...wei.com>,
        "will.deacon@....com" <will.deacon@....com>,
        "rruigrok@...eaurora.org" <rruigrok@...eaurora.org>,
        Linuxarm <linuxarm@...wei.com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "Guohanjun (Hanjun Guo)" <guohanjun@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] perf: add arm64 smmuv3 pmu driver

On 03/10/2018 09:46, Shameerali Kolothum Thodi wrote:
[...]
>>> +	/* Verify specified event is supported on this PMU */
>>> +	event_id = get_event(event);
>>> +	if (((event_id < SMMU_ARCH_MAX_EVENT_ID) &&
>>> +	    (!test_bit(event_id, smmu_pmu->supported_events))) ||
>>> +	    (event_id > SMMU_IMPDEF_MAX_EVENT_ID)) {
>>
>>> = ?
> 
> I was slightly confused by the spec here as it says,
> 
> Performance events are indicated by a numeric ID, in the following ranges:
> • 0x0000 to 0x007F: Architected events
> • 0x0080 to 0xFFFF: IMPLEMENTATION DEFINED events
> 
> It looks to me the ids are valid including those limits.

Yes my mistake, I mixed up IMPDEF_MAX_EVENT_ID which is inclusive with
ARCH_MAX_EVENT_ID which isn't, sorry about that

[...]
>>> +		dev_err(dev, "Setup irq failed, PMU @%pa\n", &res_0->start);
>>
>> You can probably remove "PMU @%pa" from error and info messages, since
>> the device name already uniquely identifies it:
>> "[    6.168200] arm-smmu-v3-pmu 2b442000.smmu-pmcg: Registered SMMU
>> PMU
>> @ 0x000000002b442000 using 4 counters"
> 
> Interesting. What I have is,
> 
> [   25.669636] arm-smmu-v3-pmu arm-smmu-v3-pmu.6.auto: Registered SMMU
> PMU @ 0x0000000148001000 using 8 counters
> 
> Are you using the same patches and is booting using ACPI? IIRC, in the iort
> code  it uses the name "arm-smmu-v3-pmu" and AUTO id to register/add the platform
> dev. So not sure, how it is printing the address in your case. 
> 
> Please check and let me know.

Right, I've been using device tree for my tests, not ACPI. I thought it
was the core platform code that was creating the names. I guess we could
add nicer names to IORT but that's probably for a different series, so
nevermind.

Thanks,
Jean