linux-kernel - Re: [PATCH v2] dt-bingdings: perf: Support uncore ARM NI-700 PMU

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Message-ID: <c68f8b00-c5df-45e1-b75a-f86ce128ddf0@arm.com>
Date: Wed, 31 Jan 2024 16:59:05 +0000
From: Robin Murphy <robin.murphy@....com>
To: Yang Jialong 杨佳龙 <jialong.yang@...ngroup.cn>,
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, will
 <will@...nel.org>, "mark.rutland" <mark.rutland@....com>
Cc: shenghui.qu@...ngroup.cn, 赵可 <ke.zhao@...ngroup.cn>,
 zhijie.ren@...ngroup.cn, linux-kernel@...r.kernel.org,
 linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
 Jonathan Cameron <jonathan.cameron@...wei.com>
Subject: Re: [PATCH v2] dt-bingdings: perf: Support uncore ARM NI-700 PMU

On 31/01/2024 10:18 am, Yang Jialong 杨佳龙 wrote:
> 
> 
> 在 2024/1/31 18:16, Krzysztof Kozlowski 写道:
>> On 31/01/2024 11:13, Yang Jialong 杨佳龙 wrote:
>>>
>>>
>>> 在 2024/1/31 17:30, Krzysztof Kozlowski 写道:
>>>> On 31/01/2024 10:26, Yang Jialong 杨佳龙 wrote:
>>>>>
>>>>>
>>>>> 在 2024/1/31 15:49, Krzysztof Kozlowski 写道:
>>>>>> On 31/01/2024 07:59, JiaLong.Yang wrote:
>>>>>>> Add file corresponding to hx_arm_ni.c introducing ARM NI-700 PMU 
>>>>>>> driver
>>>>>>> for HX.
>>>>>>>
>>>>>>> Signed-off-by: JiaLong.Yang <jialong.yang@...ngroup.cn>
>>>>>>> ---
>>>>>>> v1 --> v2:
>>>>>>> 1. Submit dt-bindings file Seperately.
>>>>>>
>>>>>> Where is the driver?
>>>>>>
>>>>>> Please read:
>>>>>> https://elixir.bootlin.com/linux/v6.8-rc2/source/Documentation/process/submitting-patches.rst
>>>>>> before posting.
>>>>>>
>>>>
>>>> Keep all discussions public.
>>>
>>> Get.
>>>
>>>>
>>>>
>>>>>>> +  pccs-id:
>>>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>>>> +    description: Used to identify NIs in system which has more than
>>>>>>> +      one NI.
>>>>>>
>>>>>> No, reg does it. Drop the property. Anyway you miss here vendor 
>>>>>> prefix
>>>>>> and proper explanation.
>>>>>>
>>>>>
>>>>> reg will tell phy address. Phy address is too long. I just want a id.
>>>>> example: perf stat -a -e ni_pmu_${pccs-id}/cycles/
>>>>> I will use it in user space. Not only in driver.
>>>>
>>>> Custom vendor property is not for that purpose. Use for example IDR, DT
>>>> aliases or something else.
>>>>
>>>>
>>>
>>> I have considered TD aliases. It's not very easy. Two places...
>>> IDR.. I have tested. But it chouldn't correspond to the HWs.
>>> I need it to identify NIs.
>>> DT aliases is reachable. But no very easy.
>>
>> Except that "you want" I did not see any rationale, any argument
>> explaining why this is needed and why this has to be present.
> 
> OK. DT aliases it good.

The real way to address that particular issue is to fix perf to properly 
associate the PMU device with the underlying hardware device. Jonathan 
had a series doing that[1], but I'm not sure what its status is now.

Thanks,
Robin.

[1] 
https://lore.kernel.org/linux-arm-kernel/20230404134225.13408-1-Jonathan.Cameron@huawei.com/