Messages in this thread | | | Subject | Re: [PATCH -next] arm64: Export __cpu_logical_map | From | Sumit Gupta <> | Date | Wed, 12 Aug 2020 01:14:49 +0530 |
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>>>>>>>> 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 >
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