linux-kernel - Re: [PATCH 2/3] soc: sifive: Add SiFive private L2 cache PMU driver

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Date:   Fri, 16 Jun 2023 21:05:17 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Eric Lin <eric.lin@...ive.com>, conor@...nel.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        palmer@...belt.com, paul.walmsley@...ive.com,
        aou@...s.berkeley.edu, maz@...nel.org, chenhuacai@...nel.org,
        baolu.lu@...ux.intel.com, will@...nel.org,
        kan.liang@...ux.intel.com, nnac123@...ux.ibm.com,
        pierre.gondois@....com, huangguangbin2@...wei.com, jgross@...e.com,
        chao.gao@...el.com, maobibo@...ngson.cn,
        linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, dslin1010@...il.com
Cc:     Greentime Hu <greentime.hu@...ive.com>,
        Zong Li <zong.li@...ive.com>, Nick Hu <nick.hu@...ive.com>
Subject: Re: [PATCH 2/3] soc: sifive: Add SiFive private L2 cache PMU driver

Le 16/06/2023 à 08:32, Eric Lin a écrit :
> From: Greentime Hu <greentime.hu@...ive.com>
> 
> This adds SiFive private L2 cache PMU driver. User
> can use perf tool to profile by event name and event id.
> 
> Example:
> $ perf stat -C 0 -e /sifive_pl2_pmu/inner_acquire_block_btot/
>                  -e /sifive_pl2_pmu/inner_acquire_block_ntob/
>                  -e /sifive_pl2_pmu/inner_acquire_block_ntot/ ls
> 
>   Performance counter stats for 'CPU(s) 0':
> 
>                 300      sifive_pl2_pmu/inner_acquire_block_btot/
>               17801      sifive_pl2_pmu/inner_acquire_block_ntob/
>                5253      sifive_pl2_pmu/inner_acquire_block_ntot/
> 
>         0.088917326 seconds time elapsed
> 
> $ perf stat -C 0 -e /sifive_pl2_pmu/event=0x10001/
>                  -e /sifive_pl2_pmu/event=0x4001/
>                  -e /sifive_pl2_pmu/event=0x8001/ ls
> 
>   Performance counter stats for 'CPU(s) 0':
> 
>                 251      sifive_pl2_pmu/event=0x10001/
>                2620      sifive_pl2_pmu/event=0x4001/
>                 644      sifive_pl2_pmu/event=0x8001/
> 
>         0.092827110 seconds time elapsed
> 
> Signed-off-by: Greentime Hu <greentime.hu@...ive.com>
> Signed-off-by: Eric Lin <eric.lin@...ive.com>
> Reviewed-by: Zong Li <zong.li@...ive.com>
> Reviewed-by: Nick Hu <nick.hu@...ive.com>
> ---

[...]

> +int sifive_pl2_pmu_probe(struct device_node	*pl2_node,
> +			 void __iomem *pl2_base, int cpu)
> +{
> +	struct sifive_pl2_pmu_event *ptr = per_cpu_ptr(&sifive_pl2_pmu_event, cpu);
> +	int ret = -EINVAL;

Nit: no need to init

> +
> +	/* Get counter numbers. */
> +	ret = of_property_read_u32(pl2_node, "sifive,perfmon-counters", &ptr->counters);
> +	if (ret) {
> +		pr_err("Not found sifive,perfmon-counters property\n");
> +		goto early_err;
> +	}
> +	pr_info("perfmon-counters: %d for CPU %d\n", ptr->counters, cpu);
> +
> +	/* Allocate perf_event. */
> +	ptr->events = kcalloc(ptr->counters, sizeof(struct perf_event), GFP_KERNEL);
> +	if (!ptr->events)
> +		return -ENOMEM;
> +
> +	ptr->event_select_base = pl2_base + SIFIVE_PL2_SELECT_BASE_OFFSET;
> +	ptr->event_counter_base = pl2_base + SIFIVE_PL2_COUNTER_BASE_OFFSET;
> +
> +	if (!pl2pmu_init_done) {
> +		ret = perf_pmu_register(sifive_pl2_pmu.pmu, sifive_pl2_pmu.pmu->name, -1);
> +		if (ret) {
> +			cpuhp_state_remove_instance(CPUHP_AP_PERF_RISCV_SIFIVE_PL2_PMU_ONLINE,
> +						    &sifive_pl2_pmu.node);
> +			pr_err("Failed to register sifive_pl2_pmu.pmu: %d\n", ret);
> +		}
> +		sifive_pl2_pmu_pm_init();
> +		pl2pmu_init_done = true;
> +	}
> +
> +	return 0;
> +
> +early_err:
> +	return ret;
> +}
> +
> +int sifive_pl2_pmu_init(void)
> +{
> +	int ret = 0;

Nit: no need to init

> +
> +	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_RISCV_SIFIVE_PL2_PMU_ONLINE,
> +				      "perf/sifive/pl2pmu:online",
> +				      sifive_pl2_pmu_online_cpu,
> +				      sifive_pl2_pmu_offline_cpu);
> +	if (ret)
> +		pr_err("Failed to register CPU hotplug notifier %d\n", ret);
> +
> +	ret = cpuhp_state_add_instance(CPUHP_AP_PERF_RISCV_SIFIVE_PL2_PMU_ONLINE,
> +				       &sifive_pl2_pmu.node);
> +	if (ret)
> +		pr_err("Failed to add hotplug instance: %d\n", ret);
> +
> +	return ret;

Nit: return 0;

> +}

[...]