linux-kernel - Re: [PATCH v2 2/3] drivers/perf: hisi: Add support for HiSilicon UC PMU driver

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Message-ID: <20230531165908.000022b0@Huawei.com>
Date:   Wed, 31 May 2023 16:59:08 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Junhao He <hejunhao3@...wei.com>
CC:     <will@...nel.org>, <linux-kernel@...r.kernel.org>,
        <mark.rutland@....com>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-doc@...r.kernel.org>, <linuxarm@...wei.com>,
        <yangyicong@...wei.com>, <shenyang39@...wei.com>,
        <prime.zeng@...ilicon.com>
Subject: Re: [PATCH v2 2/3] drivers/perf: hisi: Add support for HiSilicon UC
 PMU driver

On Wed, 31 May 2023 18:46:24 +0800
Junhao He <hejunhao3@...wei.com> wrote:

Hi Junhao,

A few small comments inline.

> On HiSilicon Hip09 platform, there is a UC (unified cache) module
> on each chip SCCL (Super CPU Cluster). UC is a cache that provides
> coherence between NUMA and UMA domains. It is located between L2
> and Memory System. While PA uncore PMU model is the same as other
> Hip09 PMU modules and many PMU events are supported. 

I don't follow what this sentence means.  Normally you'd have
While A, B is different..


> Let's support
> the PMU driver using the HiSilicon uncore PMU framework.
> 
> * rd_req_en : rd_req_en is the abbreviation of read request tracetag enable
> and allows user to count only read operations.
> details are listed in the hisi-pmu document.
Details are .. Also no need for the ine break
  and allows user to count only read operations. Details are listed
  in the hisi-pmu document at ....

> 
> * srcid_en & srcid: allows user to filter statistics that come from

Allows
for consistency with the uring_channel description that follows.

> specific CPU/ICL by configuration source ID.
> 
> * uring_channel: Allows users to filter statistical information based on
> the specified tx request uring channel.
> uring_channel only supported events: [0x47 ~ 0x59].
> 
> Signed-off-by: Junhao He <hejunhao3@...wei.com>


> diff --git a/drivers/perf/hisilicon/hisi_uncore_uc_pmu.c b/drivers/perf/hisilicon/hisi_uncore_uc_pmu.c
> new file mode 100644
> index 000000000000..d27f28584fd7
> --- /dev/null
> +++ b/drivers/perf/hisilicon/hisi_uncore_uc_pmu.c
> @@ -0,0 +1,577 @@
...




> +static int hisi_uc_pmu_init_data(struct platform_device *pdev,
> +				 struct hisi_pmu *uc_pmu)
> +{
> +	/*
> +	 * Use SCCL (Super CPU Cluster) ID and CCL (CPU Cluster) ID to
> +	 * identify the topology information of UC PMU devices in the chip.
> +	 */

>From patch description, I'd assume there is only one of these
per sccl so why do we care about the cluster level or the sub-id?
Perhaps that description is missleading?

> +	if (device_property_read_u32(&pdev->dev, "hisilicon,scl-id",
> +				     &uc_pmu->sccl_id)) {
> +		dev_err(&pdev->dev, "Can not read uc sccl-id!\n");
> +		return -EINVAL;
> +	}
> +
> +	if (device_property_read_u32(&pdev->dev, "hisilicon,ccl-id",
> +				     &uc_pmu->ccl_id)) {
> +		dev_err(&pdev->dev, "Can not read uc ccl-id!\n");
> +		return -EINVAL;
> +	}
> +
> +	if (device_property_read_u32(&pdev->dev, "hisilicon,sub-id",
> +				     &uc_pmu->sub_id)) {
> +		dev_err(&pdev->dev, "Can not read sub-id!\n");
> +		return -EINVAL;
> +	}
> +
> +	uc_pmu->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(uc_pmu->base)) {
> +		dev_err(&pdev->dev, "ioremap failed for uc_pmu resource\n");
> +		return PTR_ERR(uc_pmu->base);
> +	}
> +
> +	uc_pmu->identifier = readl(uc_pmu->base + HISI_UC_VERSION_REG);
> +
> +	return 0;
> +}


> +static struct platform_driver hisi_uc_pmu_driver = {
> +	.driver = {
> +		.name = "hisi_uc_pmu",
> +		.acpi_match_table = hisi_uc_pmu_acpi_match,
> +		/*
> +		 * We have not worked out a safe bind/unbind process,
> +		 * so this is not supported yet.

If you can reference more info on this that would be great.
Perhaps a thread talking about why?

> +		 */
> +		.suppress_bind_attrs = true,
> +	},
> +	.probe = hisi_uc_pmu_probe,
> +};