[PATCH] ACPI: processor: Add cpuidle driver check in acpi_processor_register_idle_driver

From: Tony W Wang-oc

Date: Tue May 19 2026 - 05:24:53 EST


Commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize ACPI idledriver registration") moved the ACPI idle driver registration toacpi_processor_driver_init(), but it didn't check whether a cpuidledriver was already registered.For example, on Intel platforms, if the intel_idle driver is alreadyloaded, the code would still evaluate the _CST object in the ACPItable and attempt to register the acpi_idle driver. This registrationwould fail with -EBUSY due to the existing check in cpuidle_register_driver.Add a check at the beginning of acpi_processor_register_idle_driver()to avoid unnecessary _CST evaluate and potential registration failures.--- drivers/acpi/processor_idle.c | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.cindex ee5facccbe10..0409411abb83 100644--- a/drivers/acpi/processor_idle.c+++ b/drivers/acpi/processor_idle.c@@ -1355,6 +1355,11 @@ void acpi_processor_register_idle_driver(void) int ret = -ENODEV; int cpu; + if (cpuidle_get_driver()) {+ pr_debug("cpuidle driver %pS already registered.\n", cpuidle_get_driver());+ return;+ }+ acpi_processor_update_max_cstate(); /*-- 2.25.1




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