Re: [PATCH V5 2/4] drivers/perf: imx_ddr: Add ddr performance counter support

Robin Murphy
2019-04-24T11:08:32Z

On 16/04/2019 21:39, Frank Li wrote:
[...]
> +static int ddr_perf_probe(struct platform_device *pdev)
> +{
> + struct ddr_pmu *pmu;
> + struct device_node *np;
> + void __iomem *base;
> + struct resource *iomem;
> + char *name;
> + char *hpname;
> + int num;
> + int ret;
> + u32 irq;
> + const struct of_device_id *of_id =
> + of_match_device(imx_ddr_pmu_dt_ids, &pdev->dev);
> +
> + iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + base = devm_ioremap_resource(&pdev->dev, iomem);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + np = pdev->dev.of_node;
> +
> + pmu = devm_kzalloc(&pdev->dev, sizeof(*pmu), GFP_KERNEL);
> + if (!pmu)
> + return -ENOMEM;
> +
> + num = ddr_perf_init(pmu, base, &pdev->dev);
> +
> + name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "ddr%d", num);
> + if (!name)
> + return -ENOMEM;
> +
> + hpname = devm_kasprintf(&pdev->dev, GFP_KERNEL,
> + "perf/imx/ddr%d:online", num);
> + if (!hpname)
> + return -ENOMEM;
> +
> + pmu->flags = (uintptr_t) of_id->data;
> +
> + cpumask_set_cpu(raw_smp_processor_id(), &pmu->cpu);
> + ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, hpname, NULL,
> + ddr_perf_offline_cpu);
> +
> + if (ret < 0) {
> + dev_err(&pdev->dev, "cpuhp_setup_state_multi failed\n");
> + goto ddr_perf_err;
> + }

Since you don't seem to ever remove this state again, this looks like it
would make subsequent loads of the module always fail after it's been
loaded and unloaded once - have you tried that?

Robin.

> +
> + pmu->cpuhp_state = ret;
> +
> + /* Register the pmu instance for cpu hotplug */
> + cpuhp_state_add_instance_nocalls(pmu->cpuhp_state, &pmu->node);
> +
> + ret = perf_pmu_register(&(pmu->pmu), name, -1);
> + if (ret)
> + goto ddr_perf_err;
> +
> + /* Request irq */
> + irq = of_irq_get(np, 0);
> + if (irq < 0) {
> + dev_err(&pdev->dev, "Failed to get irq: %d", irq);
> + ret = irq;
> + goto ddr_perf_irq_err;
> + }
> +
> + ret = devm_request_irq(&pdev->dev, irq,
> + ddr_perf_irq_handler,
> + IRQF_TRIGGER_RISING | IRQF_ONESHOT,
> + DDR_PERF_DEV_NAME,
> + pmu);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "Request irq failed: %d", ret);
> + goto ddr_perf_irq_err;
> + }
> +
> + return 0;
> +
> +ddr_perf_irq_err:
> + perf_pmu_unregister(&(pmu->pmu));
> +
> +ddr_perf_err:
> + if (pmu->cpuhp_state)
> + cpuhp_state_remove_instance_nocalls(pmu->cpuhp_state, &pmu->node);
> +
> + dev_warn(&pdev->dev, "i.MX8 DDR Perf PMU failed (%d), disabled\n", ret);
> + return ret;
> +}
> +
> +static int ddr_perf_remove(struct platform_device *pdev)
> +{
> + struct ddr_pmu *pmu = platform_get_drvdata(pdev);
> +
> + cpuhp_state_remove_instance_nocalls(pmu->cpuhp_state, &pmu->node);
> + perf_pmu_unregister(&pmu->pmu);
> +
> + return 0;
> +}
> +
> +static struct platform_driver imx_ddr_pmu_driver = {
> + .driver = {
> + .name = "imx-ddr-pmu",
> + .of_match_table = imx_ddr_pmu_dt_ids,
> + },
> + .probe = ddr_perf_probe,
> + .remove = ddr_perf_remove,
> +};
> +
> +static int __init imx_ddr_pmu_init(void)
> +{
> + return platform_driver_register(&imx_ddr_pmu_driver);
> +}
> +
> +module_init(imx_ddr_pmu_init);
> +