From 3ea4415015d690a51a3fb1f98dfc9a02f88f7bc4 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Mon, 20 Apr 2026 02:27:13 -0700 Subject: [PATCH] ACPI: arm64: cpuidle: Tolerate platforms with no deep PSCI idle states Commit cac173bea57d ("ACPI: processor: idle: Rework the handling of acpi_processor_ffh_lpi_probe()") moved the acpi_processor_ffh_lpi_probe() call from acpi_processor_setup_cpuidle_dev(), where its return value was ignored, to acpi_processor_get_power_info(), where it is now treated as a hard failure. As a result, platforms where psci_acpi_cpu_init_idle() returned -ENODEV stopped registering any cpuidle states, forcing CPUs to busy-poll when idle. On NVIDIA Grace (aarch64) systems with PSCIv1.1, pr->power.count is 1 (only WFI, no deep PSCI states beyond it), so the previous "count = pr->power.count - 1; if (count <= 0) return -ENODEV;" check returned -ENODEV for all 72 CPUs and disabled cpuidle entirely. The lpi_states count is already validated in acpi_processor_get_lpi_info(), so the check here is redundant. Simplify the loop to iterate over lpi_states[1..power.count). When only WFI is present, the loop body simply does not execute and the function returns 0, which is the correct outcome: there is nothing to validate for FFH and no error to report. Suggested-by: Huisong Li Cc: stable@vger.kernel.org Fixes: cac173bea57d ("ACPI: processor: idle: Rework the handling of acpi_processor_ffh_lpi_probe()") Signed-off-by: Breno Leitao Reviewed-by: Sudeep Holla Signed-off-by: Catalin Marinas --- drivers/acpi/arm64/cpuidle.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/acpi/arm64/cpuidle.c b/drivers/acpi/arm64/cpuidle.c index 801f9c450142..c68a5db8ebba 100644 --- a/drivers/acpi/arm64/cpuidle.c +++ b/drivers/acpi/arm64/cpuidle.c @@ -16,7 +16,7 @@ static int psci_acpi_cpu_init_idle(unsigned int cpu) { - int i, count; + int i; struct acpi_lpi_state *lpi; struct acpi_processor *pr = per_cpu(processors, cpu); @@ -30,14 +30,10 @@ static int psci_acpi_cpu_init_idle(unsigned int cpu) if (!psci_ops.cpu_suspend) return -EOPNOTSUPP; - count = pr->power.count - 1; - if (count <= 0) - return -ENODEV; - - for (i = 0; i < count; i++) { + for (i = 1; i < pr->power.count; i++) { u32 state; - lpi = &pr->power.lpi_states[i + 1]; + lpi = &pr->power.lpi_states[i]; /* * Only bits[31:0] represent a PSCI power_state while * bits[63:32] must be 0x0 as per ARM ACPI FFH Specification