[PATCH v3 2/2] ARM64: kernel: PSCI: move PSCI idle management code to drivers/firmware

[Russell King - ARM Linux]

On Fri, Oct 16, 2015 at 05:02:59PM +0100, Lorenzo Pieralisi wrote:
> ARM64 PSCI kernel interfaces that initialize idle states and implement
> the suspend API to enter them are generic and can be shared with the
> ARM architecture.
> 
> To achieve that goal, this patch moves ARM64 PSCI idle management
> code to drivers/firmware, so that the interface to initialize and
> enter idle states can actually be shared by ARM and ARM64 arches
> back-ends.
> 
> The ARM generic CPUidle implementation also requires the definition of
> a cpuidle_ops section entry for the kernel to initialize the CPUidle
> operations at boot based on the enable-method (ie ARM64 has the
> statically initialized cpu_ops counterparts for that purpose); therefore
> this patch also adds the required section entry on CONFIG_ARM for PSCI so
> that the kernel can initialize the PSCI CPUidle back-end when PSCI is
> the probed enable-method.
> 
> On ARM64 this patch provides no functional change.

On ARM64, it causes build breakage though:

drivers/built-in.o: In function `psci_suspend_finisher':
arm_pmu.c:(.text+0xc6494): undefined reference to `cpu_resume'
arm_pmu.c:(.text+0xc6498): undefined reference to `cpu_resume'
drivers/built-in.o: In function `psci_cpu_suspend_enter':
arm_pmu.c:(.text+0xc66c0): undefined reference to `cpu_suspend'

The code which has been moved looks similar.  However, when it lived
in arch/arm64/kernel/psci.c, it was protected by
#ifdef CONFIG_HOTPLUG_CPU.  In its new location, there are no ifdefs
around it, and so if it gets built without CONFIG_ARM_CPU_SUSPEND on
ARM, or CONFIG_CPU_PM for ARM64, it will error out like the above.

As this is causing a regression, and I've now closed my tree, I will
be doing what I said yesterday: I'll be dropping this patch for this
merge window in order to stabilise my tree.  Sorry.

-- 
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