From: Sumit Gupta <sumitg@nvidia.com>
To: Sudeep Holla <sudeep.holla@arm.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.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>,
Sumit Gupta <sumitg@nvidia.com>, Bibek Basu <bbasu@nvidia.com>
Subject: Re: [PATCH -next] arm64: Export __cpu_logical_map
Date: Sun, 26 Jul 2020 17:16:27 +0530 [thread overview]
Message-ID: <00cf6e67-16ed-872d-2c16-0ceea6b6f514@nvidia.com> (raw)
In-Reply-To: <20200724131059.GB6521@bogus>
>>> 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.
> 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.
>
> --
> Regards,
> Sudeep
>
WARNING: multiple messages have this Message-ID (diff)
From: Sumit Gupta <sumitg@nvidia.com>
To: Sudeep Holla <sudeep.holla@arm.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
"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>,
Viresh Kumar <viresh.kumar@linaro.org>,
Sumit Gupta <sumitg@nvidia.com>, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH -next] arm64: Export __cpu_logical_map
Date: Sun, 26 Jul 2020 17:16:27 +0530 [thread overview]
Message-ID: <00cf6e67-16ed-872d-2c16-0ceea6b6f514@nvidia.com> (raw)
In-Reply-To: <20200724131059.GB6521@bogus>
>>> 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.
> 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.
>
> --
> Regards,
> Sudeep
>
_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-07-26 11:46 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 ` [PATCH -next] arm64: Export __cpu_logical_map 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 [this message]
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
2020-08-11 19:44 ` Sumit Gupta
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