linux-kernel - Re: [PATCH] cpufreq: vexpress-spc: Fix wrong alternation of policy->related

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Date:   Thu, 28 Nov 2019 08:01:16 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Dietmar Eggemann <dietmar.eggemann@....com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Liviu Dudau <liviu.dudau@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Lukasz Luba <lukasz.luba@....com>, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: vexpress-spc: Fix wrong alternation of
 policy->related_cpus during CPU hp

On 27-11-19, 15:40, Sudeep Holla wrote:
> diff --git i/arch/arm/mach-vexpress/spc.c w/arch/arm/mach-vexpress/spc.c
> index 354e0e7025ae..e0e2e789a0b7 100644
> --- i/arch/arm/mach-vexpress/spc.c
> +++ w/arch/arm/mach-vexpress/spc.c
> @@ -551,8 +551,9 @@ static struct clk *ve_spc_clk_register(struct device *cpu_dev)
> 
>  static int __init ve_spc_clk_init(void)
>  {
> -       int cpu;
> +       int cpu, cluster;
>         struct clk *clk;
> +       bool init_opp_table[MAX_CLUSTERS] = { false };
> 
>         if (!info)
>                 return 0; /* Continue only if SPC is initialised */
> @@ -578,8 +579,17 @@ static int __init ve_spc_clk_init(void)
>                         continue;
>                 }
> 
> +               cluster = topology_physical_package_id(cpu_dev->id);
> +               if (init_opp_table[cluster])
> +                       continue;
> +
>                 if (ve_init_opp_table(cpu_dev))
>                         pr_warn("failed to initialise cpu%d opp table\n", cpu);
> +               else if (dev_pm_opp_set_sharing_cpus(cpu_dev,
> +                        topology_core_cpumask(cpu_dev->id)))
> +                       pr_warn("failed to mark OPPs shared for cpu%d\n", cpu);
> +
> +               init_opp_table[cluster] = true;
>         }
> 
>         platform_device_register_simple("vexpress-spc-cpufreq", -1, NULL, 0);
> diff --git i/drivers/cpufreq/vexpress-spc-cpufreq.c w/drivers/cpufreq/vexpress-spc-cpufreq.c
> index 506e3f2bf53a..83c85d3d67e3 100644
> --- i/drivers/cpufreq/vexpress-spc-cpufreq.c
> +++ w/drivers/cpufreq/vexpress-spc-cpufreq.c
> @@ -434,7 +434,7 @@ static int ve_spc_cpufreq_init(struct cpufreq_policy *policy)
>         if (cur_cluster < MAX_CLUSTERS) {
>                 int cpu;
> 
> -               cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
> +               dev_pm_opp_get_sharing_cpus(cpu_dev, policy->cpus);
> 
>                 for_each_cpu(cpu, policy->cpus)
>                         per_cpu(physical_cluster, cpu) = cur_cluster;

This is a better *work-around* I would say, as we can't break it the
way I explained earlier :)

-- 
viresh