Re: [PATCH -next] arm64: Export __cpu_logical_map

Sumit Gupta
2020-07-26T11:48:32Z

>>> 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