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Message-ID: <f0d98ab8-dcce-7cbd-7802-c818d11676f3@huawei.com>
Date: Fri, 18 Feb 2022 16:07:16 +0800
From: "liuqi (BA)" <liuqi115@...wei.com>
To: John Garry <john.garry@...wei.com>,
"will@...nel.org" <will@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>
CC: "linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Linuxarm <linuxarm@...wei.com>,
Zhangshaokun <zhangshaokun@...ilicon.com>
Subject: Re: [PATCH 1/2] drivers/perf: hisi: Add Support for CPA PMU
HiJohn,
On 2022/2/18 2:11, John Garry wrote:
> On 16/02/2022 03:16, liuqi (BA) wrote:
>>>>
>>>> + name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
>>>> "hisi_sicl%d_cpa%u", cpa_pmu->sccl_id - 1,
>>>
>>> why subtract 1? Looks dangerous if sccl_id == 0
>> As CPA PMU is on SICL, and id of SICL is 1 smaller than id of adjacent
>> SCCL. SCCL id in our Hip09 platform is set as 1, 3.... so, a
>> reasonable sccl-id will never be 0.
>
> I think that you need to view the HW IP independent of the SoC, and not
> get into the practice of relying on these things. Anyway, doesn't the
> sccl_id come from ACPI DSD (so we can set as we want)?
>
Yes, sccl_id in driver is read from ACPI DSD, and is checked in
hisi_pmu_cpu_is_associated_pmu().
>>
>> Parameters sccl_id is read from ACPI, and is checked in
>> hisi_pmu_cpu_is_associated_pmu(), so we could make sure that sccl_id
>> here is reasonable and is not 0.
>>
>>
>>>
>>>> + cpa_pmu->index_id);
>>>> +
>>>> + cpa_pmu->pmu = (struct pmu) {
>>>> + .name = name,
>>>> + .module = THIS_MODULE,
>>>> + .task_ctx_nr = perf_invalid_context,
>>>> + .event_init = hisi_uncore_pmu_event_init,
>>>> + .pmu_enable = hisi_uncore_pmu_enable,
>>>> + .pmu_disable = hisi_uncore_pmu_disable,
>>>> + .add = hisi_uncore_pmu_add,
>>>> + .del = hisi_uncore_pmu_del,
>>>> + .start = hisi_uncore_pmu_start,
>>>> + .stop = hisi_uncore_pmu_stop,
>>>> + .read = hisi_uncore_pmu_read,
>>>> + .attr_groups = cpa_pmu->pmu_events.attr_groups,
>>>> + .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
>>>> + };
>>>> +
>>>> + ret = perf_pmu_register(&cpa_pmu->pmu, name, -1);
>>>> + if (ret) {
>>>> + dev_err(cpa_pmu->dev, "CPA PMU register failed\n");
>>>> + cpuhp_state_remove_instance_nocalls(
>>>> + CPUHP_AP_PERF_ARM_HISI_CPA_ONLINE, &cpa_pmu->node);
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int hisi_cpa_pmu_remove(struct platform_device *pdev)
>>>> +{
>>>> + struct hisi_pmu *cpa_pmu = platform_get_drvdata(pdev);
>>>> +
>>>> + perf_pmu_unregister(&cpa_pmu->pmu);
>>>> +
>>>> cpuhp_state_remove_instance_nocalls(CPUHP_AP_PERF_ARM_HISI_CPA_ONLINE,
>>>> + &cpa_pmu->node);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static struct platform_driver hisi_cpa_pmu_driver = {
>>>> + .driver = {
>>>> + .name = "hisi_cpa_pmu",
>>>> + .acpi_match_table = ACPI_PTR(hisi_cpa_pmu_acpi_match),
>>>> + .suppress_bind_attrs = true,
>>>> + },
>>>> + .probe = hisi_cpa_pmu_probe,
>>>> + .remove = hisi_cpa_pmu_remove,
>>>> +};
>>>> +
>>>> +static int __init hisi_cpa_pmu_module_init(void)
>>>> +{
>>>> + int ret;
>>>> +
>>>> + ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_HISI_CPA_ONLINE,
>>>> + "AP_PERF_ARM_HISI_CPA_ONLINE",
>>>> + hisi_uncore_pmu_online_cpu,
>>>> + hisi_uncore_pmu_offline_cpu);
>>>> + if (ret) {
>>>> + pr_err("CPA PMU: setup hotplug: %d\n", ret);
>>>> + return ret;
>>>> + }
>>>> +
>>>> + ret = platform_driver_register(&hisi_cpa_pmu_driver);
>>>> + if (ret)
>>>> + cpuhp_remove_multi_state(CPUHP_AP_PERF_ARM_HISI_CPA_ONLINE);
>>>
>>> I am not being totally serious, but this pattern of registering a CPU
>>> hotplug handler and then a driver is so common that we could nearly
>>> add a wrapper for it.
>>>
>>
>> Hi John, do you mean somthing like this?
>>
>> in hisi_uncore_pmu.c:
>>
>> int hisi_uncore_pmu_module_init(enum cpuhp_state state, const char
>> *name, struct platform_driver *drv)
>> {
>> int ret;
>>
>> ret = cpuhp_setup_state_multi(state, name,
>> hisi_uncore_pmu_online_cpu,
>> hisi_uncore_pmu_offline_cpu);
>> if (ret) {
>> pr_err("%s: setup hotplug: %d\n", drv->driver.name, ret);
>> return ret;
>> }
>>
>> ret = platform_driver_register(drv);
>> if (ret)
>> cpuhp_remove_multi_state(state);
>>
>> return ret;
>> }
>>
>> in hisi_uncore_cpa_pmu.c:
>>
>> static int __init hisi_cpa_pmu_module_init(void)
>> {
>> int ret;
>>
>> ret = hisi_uncore_pmu_module_init(CPUHP_AP_PERF_ARM_HISI_CPA_ONLINE,
>> "AP_PERF_ARM_HISI_CPA_ONLINE",
>> &hisi_cpa_pmu_driver);
>>
>> return ret;
>> }
>> module_init(hisi_cpa_pmu_module_init);
>
> Sure, but I'm talking about going further and having this as
> drivers/perf or even platform_device.h helper:
>
> diff --git a/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> b/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> index 62299ab5a9be..22f635260a5f 100644
> --- a/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> +++ b/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> @@ -562,26 +562,11 @@ static struct platform_driver hisi_ddrc_pmu_driver
> = {
> .remove = hisi_ddrc_pmu_remove,
> };
>
> -static int __init hisi_ddrc_pmu_module_init(void)
> -{
> - int ret;
> -
> - ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_HISI_DDRC_ONLINE,
> - "AP_PERF_ARM_HISI_DDRC_ONLINE",
> - hisi_uncore_pmu_online_cpu,
> - hisi_uncore_pmu_offline_cpu);
> - if (ret) {
> - pr_err("DDRC PMU: setup hotplug, ret = %d\n", ret);
> - return ret;
> - }
> -
> - ret = platform_driver_register(&hisi_ddrc_pmu_driver);
> - if (ret)
> - cpuhp_remove_multi_state(CPUHP_AP_PERF_ARM_HISI_DDRC_ONLINE);
> +module_platform_driver_cpu_hotplug(hisi_ddrc_pmu_driver,
> + AP_PERF_ARM_HISI_DDRC_ONLINE,
> + hisi_uncore_pmu_online_cpu,
> + hisi_uncore_pmu_online_cpu);
>
> - return ret;
> -}
> -module_init(hisi_ddrc_pmu_module_init);
>
> static void __exit hisi_ddrc_pmu_module_exit(void)
> {
> diff --git a/include/linux/platform_device.h
> b/include/linux/platform_device.h
> index 7c96f169d274..d0816dfc0637 100644
> --- a/include/linux/platform_device.h
> +++ b/include/linux/platform_device.h
> @@ -261,6 +261,28 @@ static inline void platform_set_drvdata(struct
> platform_device *pdev,
> #define builtin_platform_driver(__platform_driver) \
> builtin_driver(__platform_driver, platform_driver_register)
>
> +#define module_platform_driver_cpu_hotplug(__platform_driver,
> cpuhp_state, online, offline) \
> +static int __init
> __module_platform_driver_cpu_hotplug##_init(void) \
> +{ \
> + int ret; \
> + ret = cpuhp_setup_state_multi(CPUHP_##cpuhp_state, \
> + "##cpuhp_state", \
> + online, \
> + offline); \
> + if (ret) { \
> + pr_err("setup hotplug, ret = %d\n", ret); \
> + return ret; \
> + } \
> + \
> + ret = platform_driver_register(&__platform_driver); \
> + if (ret) \
> + cpuhp_remove_multi_state(CPUHP_##cpuhp_state); \
> + \
> + return ret; \
> +} \
> +module_init(__module_platform_driver_cpu_hotplug##_init);
> +
> +
got it, I think we could make another patch to do these cleanup.
Thanks,
Qi
> /* module_platform_driver_probe() - Helper macro for drivers that
> don't do
> * anything special in module init/exit. This eliminates a lot of
> * boilerplate. Each module may only use this macro once, and
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