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From: Sumit Gupta <sumitg@nvidia.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>,
	Will Deacon <will@kernel.org>,
	Mikko Perttunen <mperttunen@nvidia.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Hulk Robot <hulkci@huawei.com>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	Bibek Basu <bbasu@nvidia.com>,
	linux-tegra <linux-tegra@vger.kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jon Hunter <jonathanh@nvidia.com>
Subject: Re: [PATCH -next] arm64: Export __cpu_logical_map
Date: Wed, 12 Aug 2020 01:14:49 +0530	[thread overview]
Message-ID: <f80a58ac-4f6f-a1c8-182b-7de237e47157@nvidia.com> (raw)
In-Reply-To: <20200810101954.GA9480@gaia>



>>>>>>>> ERROR: modpost: "__cpu_logical_map" [drivers/cpufreq/tegra194-cpufreq.ko] undefined!
>>>>>>>>
>>>>>>>> ARM64 tegra194-cpufreq driver use cpu_logical_map, export
>>>>>>>> __cpu_logical_map to fix build issue.
>>>>>>>>
>>>>>>
>>>>>> I wonder why like other instances in the drivers, the mpidr is not get
>>>>>> directly from the cpu. The cpufreq_driver->init call happens when the cpu
>>>>>> is being brought online and is executed on the required cpu IIUC.
>>>>>
>>>>> Yes, this occurs during hotplug case.
>>>>> But in the case of system boot, 'cpufreq_driver->init' is called later
>>>>> during cpufreq platform driver's probe. The value of CPU in 'policy->cpu'
>>>>> can be different from the current CPU. That's why read_cpuid_mpidr() can't
>>>>> be used.
>>>>
>>>> Fair enough, why not do cross call like in set_target ? Since it is one-off
>>>> in init, I don't see any issue when you are doing it runtime for set_target.
>>>>
>>>>>> read_cpuid_mpidr() is inline and avoids having to export the logical_cpu_map.
>>>>>> Though we may not add physical hotplug anytime soon, less dependency
>>>>>> on this cpu_logical_map is better given that we can resolve this without
>>>>>> the need to access the map.
>>>>
>>>> To be honest, we have tried to remove all the dependency on cluster id
>>>> in generic code as it is not well defined. This one is tegra specific
>>>> driver so should be fine. But I am still bit nervous to export
>>>> cpu_logical_map as we have no clue what that would mean for physical
>>>> hotplug.
>>>
>>> As suggested, I have done below change to get the cluster number using
>>> read_cpuid_mpidr(). Please review and suggest if this looks ok?
>>> I will send formal patch if the change is fine.
>>>
>>> diff --git a/drivers/cpufreq/tegra194-cpufreq.c
>>> b/drivers/cpufreq/tegra194-cpufreq.c
>>> index bae527e..06f5ccf 100644
>>> --- a/drivers/cpufreq/tegra194-cpufreq.c
>>> +++ b/drivers/cpufreq/tegra194-cpufreq.c
>>> @@ -56,9 +56,11 @@ struct read_counters_work {
>>>
>>>   static struct workqueue_struct *read_counters_wq;
>>>
>>> -static enum cluster get_cpu_cluster(u8 cpu)
>>> +static void get_cpu_cluster(void *cluster)
>>>   {
>>> -       return MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
>>> +       u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
>>> +
>>> +       *((uint32_t *) cluster) = MPIDR_AFFINITY_LEVEL(mpidr, 1);
>>>   }
>>>
>>>   /*
>>> @@ -186,8 +188,10 @@ static unsigned int tegra194_get_speed(u32 cpu)
>>>   static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
>>>   {
>>>          struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
>>> -       int cl = get_cpu_cluster(policy->cpu);
>>>          u32 cpu;
>>> +       u32 cl;
>>> +
>>> +       smp_call_function_single(policy->cpu, get_cpu_cluster, &cl, true);
>>
>> Thanks for this, looks good to me. You can add:
>>
>> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> 
> I already merged Kefeng's __cpu_logical_map fix (commit eaecca9e7710)
> but if the above goes in, I can drop the EXPORT_SYMBOL part (and keep
> the rest as it's a good refactoring).
> 
I have posted the formal patch.

Thanks,
Sumit

> --
> Catalin
> 

WARNING: multiple messages have this Message-ID
From: Sumit Gupta <sumitg@nvidia.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>,
	Mikko Perttunen <mperttunen@nvidia.com>,
	Hulk Robot <hulkci@huawei.com>, Bibek Basu <bbasu@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	linux-tegra <linux-tegra@vger.kernel.org>,
	Jon Hunter <jonathanh@nvidia.com>, Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH -next] arm64: Export __cpu_logical_map
Date: Wed, 12 Aug 2020 01:14:49 +0530	[thread overview]
Message-ID: <f80a58ac-4f6f-a1c8-182b-7de237e47157@nvidia.com> (raw)
In-Reply-To: <20200810101954.GA9480@gaia>



>>>>>>>> ERROR: modpost: "__cpu_logical_map" [drivers/cpufreq/tegra194-cpufreq.ko] undefined!
>>>>>>>>
>>>>>>>> ARM64 tegra194-cpufreq driver use cpu_logical_map, export
>>>>>>>> __cpu_logical_map to fix build issue.
>>>>>>>>
>>>>>>
>>>>>> I wonder why like other instances in the drivers, the mpidr is not get
>>>>>> directly from the cpu. The cpufreq_driver->init call happens when the cpu
>>>>>> is being brought online and is executed on the required cpu IIUC.
>>>>>
>>>>> Yes, this occurs during hotplug case.
>>>>> But in the case of system boot, 'cpufreq_driver->init' is called later
>>>>> during cpufreq platform driver's probe. The value of CPU in 'policy->cpu'
>>>>> can be different from the current CPU. That's why read_cpuid_mpidr() can't
>>>>> be used.
>>>>
>>>> Fair enough, why not do cross call like in set_target ? Since it is one-off
>>>> in init, I don't see any issue when you are doing it runtime for set_target.
>>>>
>>>>>> read_cpuid_mpidr() is inline and avoids having to export the logical_cpu_map.
>>>>>> Though we may not add physical hotplug anytime soon, less dependency
>>>>>> on this cpu_logical_map is better given that we can resolve this without
>>>>>> the need to access the map.
>>>>
>>>> To be honest, we have tried to remove all the dependency on cluster id
>>>> in generic code as it is not well defined. This one is tegra specific
>>>> driver so should be fine. But I am still bit nervous to export
>>>> cpu_logical_map as we have no clue what that would mean for physical
>>>> hotplug.
>>>
>>> As suggested, I have done below change to get the cluster number using
>>> read_cpuid_mpidr(). Please review and suggest if this looks ok?
>>> I will send formal patch if the change is fine.
>>>
>>> diff --git a/drivers/cpufreq/tegra194-cpufreq.c
>>> b/drivers/cpufreq/tegra194-cpufreq.c
>>> index bae527e..06f5ccf 100644
>>> --- a/drivers/cpufreq/tegra194-cpufreq.c
>>> +++ b/drivers/cpufreq/tegra194-cpufreq.c
>>> @@ -56,9 +56,11 @@ struct read_counters_work {
>>>
>>>   static struct workqueue_struct *read_counters_wq;
>>>
>>> -static enum cluster get_cpu_cluster(u8 cpu)
>>> +static void get_cpu_cluster(void *cluster)
>>>   {
>>> -       return MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1);
>>> +       u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
>>> +
>>> +       *((uint32_t *) cluster) = MPIDR_AFFINITY_LEVEL(mpidr, 1);
>>>   }
>>>
>>>   /*
>>> @@ -186,8 +188,10 @@ static unsigned int tegra194_get_speed(u32 cpu)
>>>   static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
>>>   {
>>>          struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
>>> -       int cl = get_cpu_cluster(policy->cpu);
>>>          u32 cpu;
>>> +       u32 cl;
>>> +
>>> +       smp_call_function_single(policy->cpu, get_cpu_cluster, &cl, true);
>>
>> Thanks for this, looks good to me. You can add:
>>
>> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> 
> I already merged Kefeng's __cpu_logical_map fix (commit eaecca9e7710)
> but if the above goes in, I can drop the EXPORT_SYMBOL part (and keep
> the rest as it's a good refactoring).
> 
I have posted the formal patch.

Thanks,
Sumit

> --
> Catalin
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2020-08-11 19:45 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200724030433.22287-1-wangkefeng.wang@huawei.com>
2020-07-24  3:08 ` Kefeng Wang
2020-07-24  3:08   ` Kefeng Wang
2020-07-24  8:16   ` Anshuman Khandual
2020-07-24  8:16     ` Anshuman Khandual
2020-07-24  9:13     ` Mark Rutland
2020-07-24  9:13       ` Mark Rutland
2020-07-24  9:35       ` Catalin Marinas
2020-07-24  9:35         ` Catalin Marinas
2020-07-24 10:33         ` Anshuman Khandual
2020-07-24 10:33           ` Anshuman Khandual
2020-07-24  9:16     ` Kefeng Wang
2020-07-24  9:16       ` Kefeng Wang
2020-07-24  9:30     ` Catalin Marinas
2020-07-24  9:30       ` Catalin Marinas
2020-07-24 10:36       ` Anshuman Khandual
2020-07-24 10:36         ` Anshuman Khandual
2020-07-24  9:43   ` Christoph Hellwig
2020-07-24  9:43     ` Christoph Hellwig
2020-07-24 13:10   ` Sudeep Holla
2020-07-24 13:10     ` Sudeep Holla
2020-07-25  2:00     ` Kefeng Wang
2020-07-25  2:00       ` Kefeng Wang
2020-07-26 11:46     ` Sumit Gupta
2020-07-26 11:46       ` Sumit Gupta
2020-07-27 16:05       ` Sudeep Holla
2020-07-27 16:05         ` Sudeep Holla
2020-08-01 12:16         ` Sumit Gupta
2020-08-01 12:16           ` Sumit Gupta
2020-08-10  7:49           ` Sudeep Holla
2020-08-10  7:49             ` Sudeep Holla
2020-08-10 10:19             ` Catalin Marinas
2020-08-10 10:19               ` Catalin Marinas
2020-08-10 12:11               ` Sudeep Holla
2020-08-10 12:11                 ` Sudeep Holla
2020-08-11 19:44               ` Sumit Gupta [this message]
2020-08-11 19:44                 ` Sumit Gupta

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