ACPI: processor: perflib: Fix initial _PPC limit application

If the BIOS sets a _PPC frequency limit upfront, it will fail to take
effect due to a call ordering issue.  Namely, freq_qos_update_request()
is called before freq_qos_add_request() for the given request causing
the constraint update to be ignored.  The call sequence in question is
as follows:

cpufreq_policy_online()
  acpi_cpufreq_cpu_init()
    acpi_processor_register_performance()
      acpi_processor_get_performance_info()
        acpi_processor_get_platform_limit()
         freq_qos_update_request(&perflib_req) <- inactive QoS request
  blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
                               CPUFREQ_CREATE_POLICY)
    acpi_processor_notifier()
      acpi_processor_ppc_init()
        freq_qos_add_request(&perflib_req) <- QoS request activation

Address this by adding an acpi_processor_get_platform_limit() call
to acpi_processor_ppc_init(), after the perflib_req activation via
freq_qos_add_request(), which causes the initial _PPC limit to be
picked up as appropriate.  However, also ensure that the _PPC limit
will not be picked up in the cases when the cpufreq driver does not
call acpi_processor_register_performance() by adding a pr->performance
check to the related_cpus loop in acpi_processor_ppc_init().

Fixes: d15ce412737a ("ACPI: cpufreq: Switch to QoS requests instead of cpufreq notifier")
Signed-off-by: Jiayi Li <lijiayi@kylinos.cn>
Link: https://patch.msgid.link/20250721032606.3459369-1-lijiayi@kylinos.cn
[ rjw: Consolidate pr-related checks in acpi_processor_ppc_init() ]
[ rjw: Subject and changelog adjustments ]
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+: 2d8b39a62a5d ACPI: processor: Avoid NULL pointer dereferences at init time
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+: 3000ce3c52f8 cpufreq: Use per-policy frequency QoS
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+: a1bb46c36ce3 ACPI: processor: Add QoS requests for all CPUs
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions