@@ -11,6 +11,11 @@
/* Refer to drivers/acpi/cppc_acpi.c for the description of functions */
+bool cpc_supported_by_cpu(void)
+{
+ return boot_cpu_has(X86_FEATURE_CPPC);
+}
+
bool cpc_ffh_supported(void)
{
return true;
@@ -577,6 +577,19 @@ bool __weak cpc_ffh_supported(void)
return false;
}
+/**
+ * cpc_supported_by_cpu() - check if CPPC is supported by CPU
+ *
+ * Check if the architectural support for CPPC is present even
+ * if the _OSC hasn't prescribed it
+ *
+ * Return: true for supported, false for not supported
+ */
+bool __weak cpc_supported_by_cpu(void)
+{
+ return false;
+}
+
/**
* pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
*
@@ -686,7 +699,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
if (!osc_sb_cppc2_support_acked) {
pr_debug("CPPC v2 _OSC not acked\n");
- return -ENODEV;
+ if (!cpc_supported_by_cpu())
+ return -ENODEV;
}
/* Parse the ACPI _CPC table for this CPU. */
@@ -145,6 +145,7 @@ extern bool cppc_allow_fast_switch(void);
extern int acpi_get_psd_map(unsigned int cpu, struct cppc_cpudata *cpu_data);
extern unsigned int cppc_get_transition_latency(int cpu);
extern bool cpc_ffh_supported(void);
+extern bool cpc_supported_by_cpu(void);
extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
#else /* !CONFIG_ACPI_CPPC_LIB */
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 a dedicated MSR from `X86_FEATURE_CPPC`, use this enable this feature rather than requiring the `_OSC` on platforms with a dedicated MSR. If there is additional breakage on the shared memory designs also missing this _OSC, additional follow up changes may be needed. Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is supported") Reported-by: Perry Yuan <perry.yuan@amd.com> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> --- v2->v3 * Rebase on top of solution for _CPC regression on some Intel systemss * Refactor to avoid #ifdef CONFIG_X86 arch/x86/kernel/acpi/cppc.c | 5 +++++ drivers/acpi/cppc_acpi.c | 16 +++++++++++++++- include/acpi/cppc_acpi.h | 1 + 3 files changed, 21 insertions(+), 1 deletion(-)