linux-kernel - Re: [PATCH -next] arm64: Export __cpu_logical

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Date:   Sat, 25 Jul 2020 10:00:35 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Sudeep Holla <sudeep.holla@....com>
CC:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Sumit Gupta <sumitg@...dia.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Hulk Robot <hulkci@...wei.com>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <hch@...radead.org>,
        "Anshuman Khandual" <anshuman.khandual@....com>
Subject: Re: [PATCH -next] arm64: Export __cpu_logical_map


On 2020/7/24 21:10, Sudeep Holla wrote:
> On Fri, Jul 24, 2020 at 11:08:03AM +0800, Kefeng Wang wrote:
>> +maillist
>>
>> On 2020/7/24 11:04, Kefeng Wang wrote:
>>> 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.
>
> 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.

Hi all,  thanks for all comments.

As Sudeep said, I will using read_cpuid_mpidr() directly in 
tegra194-cpufreq to

fix the build issue,  and later we also would turn cpu_logical_map() 
into a C wrapper.

If that's ok, I will send a new build-fix patch firstly, thanks.


>