[PATCH V2] arm64: skip register_cpufreq_notifier on ACPI-based systems

[will.deacon@arm.com (Will Deacon)]

On Thu, Jan 26, 2017 at 11:08:32AM -0700, Prashanth Prakash wrote:
> On ACPI based systems where the topology is setup using the API
> store_cpu_topology, at the moment we do not have necessary code
> to parse cpu capacity and handle cpufreq notifier, thus
> resulting in a kernel panic.
> 
> Stack:
>         init_cpu_capacity_callback+0xb4/0x1c8
>         notifier_call_chain+0x5c/0xa0
>         __blocking_notifier_call_chain+0x58/0xa0
>         blocking_notifier_call_chain+0x3c/0x50
>         cpufreq_set_policy+0xe4/0x328
>         cpufreq_init_policy+0x80/0x100
>         cpufreq_online+0x418/0x710
>         cpufreq_add_dev+0x118/0x180
>         subsys_interface_register+0xa4/0xf8
>         cpufreq_register_driver+0x1c0/0x298
>         cppc_cpufreq_init+0xdc/0x1000 [cppc_cpufreq]
>         do_one_initcall+0x5c/0x168
>         do_init_module+0x64/0x1e4
>         load_module+0x130c/0x14d0
>         SyS_finit_module+0x108/0x120
>         el0_svc_naked+0x24/0x28
> 
> Fixes: 7202bde8b7ae ("arm64: parse cpu capacity-dmips-mhz from DT")
> Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
> ---
>  arch/arm64/kernel/topology.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Acked-by: Will Deacon <will.deacon@arm.com>

Catalin -- this resolves a panic, so please take it for 4.10

Will