cpufreq: CPPC: Select the frequency-invariance callback per CPU

cppc_cpufreq_cpu_fie_init() initializes deferred work only for CPUs whose
feedback counters use PCC. However, if any CPU in a shared policy uses PCC,
it installs the PCC tick callback for the entire policy. With FIE enabled,
a non-PCC CPU then queues an uninitialized irq_work and can call a NULL
function pointer when that work runs.

Choose the frequency-invariance callback separately for each CPU using
the recorded work-initialization state. Processor removal can unpublish
the CPC descriptor before callback registration, so querying its counter
transport again can incorrectly select direct reads for a PCC CPU.

Register the callbacks after all counter initialization has completed, so
a failed initial read for an online CPU cannot leave a partially
registered policy. PCC CPUs use their initialized deferred work, while
non-PCC CPUs read their own counters directly from the tick.

Fixes: 997c021abc6e ("cpufreq: CPPC: Update FIE arch_freq_scale in ticks for non-PCC regs")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Sumit Gupta <sumitg@nvidia.com>
Link: https://patch.msgid.link/20260916162805.1039247-20-christian.loehle@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions