cpufreq: CPPC: Create the FIE worker before enabling PCC callbacks

cppc_freq_invariance_init() creates the PCC worker only if an online CPU
currently has PCC counters. A shared policy can also initialize an offline
PCC member. When that CPU comes online, its callback queues work through
the missing kworker_fie and dereferences NULL. A later hot-added PCC policy
can encounter the same missing worker.

Create the worker when policy initialization encounters PCC counters,
before initializing their work and publishing any callbacks. Serialize
creation and reuse the worker until driver teardown. This covers offline
policy members and later PCC policies without creating an unused deadline
worker on direct-counter-only systems.

If worker allocation or scheduling setup fails, leave FIE unregistered for
that policy. Keep the global FIE setting unchanged so direct-counter
policies remain independent of worker setup and existing policies still
drain their initialized work during teardown. Publish kworker_fie only
after successful setup, allowing a later policy initialization to retry.

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/20260916162805.1039247-21-christian.loehle@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions