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Subject: Re: [PATCH v6 4/4] perf/smmuv3_pmu: Enable HiSilicon Erratum
 162001800 quirk
To:     Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
        <lorenzo.pieralisi@arm.com>, <robin.murphy@arm.com>
CC:     <andrew.murray@arm.com>, <jean-philippe.brucker@arm.com>,
        <will.deacon@arm.com>, <mark.rutland@arm.com>,
        <john.garry@huawei.com>, <pabba@codeaurora.org>,
        <vkilari@codeaurora.org>, <rruigrok@codeaurora.org>,
        <linux-acpi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linuxarm@huawei.com>,
        <neil.m.leeder@gmail.com>
References: <20190204121324.11460-1-shameerali.kolothum.thodi@huawei.com>
 <20190204121324.11460-5-shameerali.kolothum.thodi@huawei.com>
From:   Hanjun Guo <guohanjun@huawei.com>
Message-ID: <91fa1e08-a905-90a9-3577-fa3486bb951f@huawei.com>
Date:   Thu, 14 Feb 2019 15:29:41 +0800
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On 2019/2/4 20:13, Shameer Kolothum wrote:
> HiSilicon erratum 162001800 describes the limitation of
> SMMUv3 PMCG implementation on HiSilicon Hip08 platforms.
> 
> On these platforms, the PMCG event counter registers
> (SMMU_PMCG_EVCNTRn) are read only and as a result it
> is not possible to set the initial counter period value
> on event monitor start.
> 
> To work around this, the current value of the counter
> is read and used for delta calculations. OEM information
> from ACPI header is used to identify the affected hardware
> platforms.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
>  drivers/acpi/arm64/iort.c     | 16 ++++++++++++++-
>  drivers/perf/arm_smmuv3_pmu.c | 48 ++++++++++++++++++++++++++++++++++++-------
>  include/linux/acpi_iort.h     |  1 +
>  3 files changed, 57 insertions(+), 8 deletions(-)

For this patch,

Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks
Hanjun