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From:   John Garry <john.garry@huawei.com>
Subject: Re: [PATCH] drivers/perf: hisi: Add identifier sysfs file
To:     Will Deacon <will@kernel.org>
CC:     <zhangshaokun@hisilicon.com>, <mark.rutland@arm.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <qiangqing.zhang@nxp.com>,
        <jolsa@redhat.com>, <linuxarm@huawei.com>,
        Robin Murphy <robin.murphy@arm.com>
References: <1592399111-134786-1-git-send-email-john.garry@huawei.com>
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Message-ID: <f9ef4f4f-beeb-7898-0655-3cd682605b93@huawei.com>
Date:   Thu, 1 Oct 2020 09:34:02 +0100
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On 15/07/2020 09:30, Will Deacon wrote:
> Hi John,
> 
> On Wed, Jul 15, 2020 at 09:23:19AM +0100, John Garry wrote:
>>> On Wed, Jun 17, 2020 at 09:05:11PM +0800, John Garry wrote:
>>>> To allow userspace to identify the specific implementation of the device,
>>>> add an "identifier" sysfs file.
>>>>
>>>> Encoding is as follows:
>>>> hi1620: 0x0	(aka hip08)
>>>> hi1630: 0x30
>>>>
>>>> Signed-off-by: John Garry <john.garry@huawei.com>
>>>
>>> I'm struggling a bit to track this. If you still think it's worth pursuing,
>>> please could you post a series with a cover-letter describing what this is
>>> for, a link to the userspace changes and then patches for all the PMU
>>> drivers that need updating?
>>
>> There is no hi1630 userspace support yet.
>>
>> So what I can do is post updated userspace support (including hi1630), and
>> then post kernel parts together for all drivers we could initially support.
>>
>> @Joakim, I'll pick your imx driver changes here, if you don't mind.
>>
>> There was an RFC from you for the SMMUv3 PMU as
>>> well, and also some other "arm64" changes.
>>>
>>
>> I hope to drop that RFC if an updated SMMUv3 spec helps us out.
> 

Released SMMUv3.3 spec provides a PMCG_IIDR reg, which we can now use to 
identify the implementation:

https://developer.arm.com/documentation/ihi0070/da/?lang=en

So I'll look to put the userspace and kernel parts together for this now 
for review.

Thanks,
John