linux-kernel - Re: [PATCH v5 3/6] perf: hisi: Add support for HiSilicon SoC L3C PMU driver

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Date:   Tue, 17 Oct 2017 16:16:58 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Shaokun Zhang <zhangshaokun@...ilicon.com>
Cc:     will.deacon@....com, jonathan.cameron@...wei.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linuxarm@...wei.com,
        Anurup M <anurup.m@...wei.com>
Subject: Re: [PATCH v5 3/6] perf: hisi: Add support for HiSilicon SoC L3C PMU
 driver

On Tue, Aug 22, 2017 at 04:07:54PM +0800, Shaokun Zhang wrote:
> +static int hisi_l3c_pmu_init_irq(struct hisi_pmu *l3c_pmu,
> +				 struct platform_device *pdev)
> +{
> +	int irq, ret;
> +
> +	/* Read and init IRQ */
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "L3C PMU get irq fail; irq:%d\n", irq);
> +		return irq;
> +	}
> +
> +	ret = devm_request_irq(&pdev->dev, irq, hisi_l3c_pmu_isr,
> +			       IRQF_NOBALANCING | IRQF_NO_THREAD,
> +			       dev_name(&pdev->dev), l3c_pmu);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev,
> +			"Fail to request IRQ:%d ret:%d\n", irq, ret);
> +		return ret;
> +	}
> +
> +	l3c_pmu->irq = irq;
> +
> +	return 0;
> +}
> +
> +/*
> + * Check whether the CPU is associated with this L3C PMU by SCCL_ID
> + * and CCL_ID, if true, set the associated cpumask of the L3C PMU.
> + */
> +static void hisi_l3c_pmu_set_cpumask_by_ccl(void *arg)
> +{
> +	struct hisi_pmu *l3c_pmu = (struct hisi_pmu *)arg;
> +	u32 ccl_id, sccl_id;
> +
> +	hisi_read_sccl_and_ccl_id(&sccl_id, &ccl_id);
> +	if (sccl_id == l3c_pmu->sccl_id && ccl_id == l3c_pmu->ccl_id)
> +		cpumask_set_cpu(smp_processor_id(), &l3c_pmu->associated_cpus);
> +}

The shared code has hisi_uncore_pmu_set_cpumask_by_sccl(), and it would
be nice to place this in the same place.

Otherwise, the same comments apply here.

> +
> +static const struct acpi_device_id hisi_l3c_pmu_acpi_match[] = {
> +	{ "HISI0213", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(acpi, hisi_l3c_pmu_acpi_match);
> +
> +static int hisi_l3c_pmu_init_data(struct platform_device *pdev,
> +				  struct hisi_pmu *l3c_pmu)
> +{
> +	unsigned long long id;
> +	struct resource *res;
> +	acpi_status status;
> +	int cpu;
> +
> +	status = acpi_evaluate_integer(ACPI_HANDLE(&pdev->dev),
> +				       "_UID", NULL, &id);
> +	if (ACPI_FAILURE(status))
> +		return -EINVAL;
> +
> +	l3c_pmu->id = id;
> +
> +	/*
> +	 * Use the SCCL_ID and CCL_ID to identify the L3C PMU, while
> +	 * SCCL_ID is in MPIDR[aff2] and CCL_ID is in MPIDR[aff1].
> +	 */
> +	if (device_property_read_u32(&pdev->dev, "hisilicon,scl-id",
> +				     &l3c_pmu->sccl_id)) {
> +		dev_err(&pdev->dev, "Can not read l3c sccl-id!\n");
> +		return -EINVAL;
> +	}
> +
> +	if (device_property_read_u32(&pdev->dev, "hisilicon,ccl-id",
> +				     &l3c_pmu->ccl_id)) {
> +		dev_err(&pdev->dev, "Can not read l3c ccl-id!\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Initialise the associated cpumask of the PMU */
> +	for_each_present_cpu(cpu)
> +		smp_call_function_single(cpu, hisi_l3c_pmu_set_cpumask_by_ccl,
> +					 (void *)l3c_pmu, 1);

Ah, so that's why hisi_uncore_pmu_set_cpumask_by_sccl took a void
pointer.

Please drop a comment above hisi_uncore_pmu_set_cpumask_by_sccl to cover
that.

I think you can drop the void cast here; I don't beleive it is
necessary.

Rather than a proble-time smp_call_function_single(), can you follow the
qcom l2's approach of associating CPUs with a PMU instance in the
notifier? That will work even if CPUs are brought online very late.

> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	l3c_pmu->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(l3c_pmu->base)) {
> +		dev_err(&pdev->dev, "ioremap failed for l3c_pmu resource\n");
> +		return PTR_ERR(l3c_pmu->base);
> +	}
> +
> +	return 0;
> +}

Thanks,
Mark.