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Subject[PATCH] ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is supported
commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
when CPPC_LIB is supported") added support for claiming to
support CPPC in _OSC on non-Intel platforms.

This unfortunately caused a regression on a vartiety of AMD
platforms in the field because a number of AMD platforms don't set
the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.

As these AMD platforms already claim CPPC support via `X86_FEATURE_CPPC`,
use this enable this feature rather than requiring the `_OSC`.

Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is supported")
Reported-by: Perry Yuan <>
Signed-off-by: Mario Limonciello <>
drivers/acpi/cppc_acpi.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 903528f7e187..5463e6309b9a 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int num_ent)
return false;

+ if (osc_sb_cppc_not_supported) {
+ pr_debug("Firmware missing _OSC support\n");
+#ifdef CONFIG_X86
+ return boot_cpu_has(X86_FEATURE_CPPC);
+ return false;
+ }
return true;

@@ -684,9 +693,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
acpi_status status;
int ret = -ENODATA;

- if (osc_sb_cppc_not_supported)
- return -ENODEV;
/* Parse the ACPI _CPC table for this CPU. */
status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
 \ /
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