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-rw-r--r--drivers/acpi/cppc_acpi.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 6f09fe011544..840223c12540 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -100,6 +100,16 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
(cpc)->cpc_entry.reg.space_id == \
ACPI_ADR_SPACE_PLATFORM_COMM)
+/* Check if a CPC register is in SystemMemory */
+#define CPC_IN_SYSTEM_MEMORY(cpc) ((cpc)->type == ACPI_TYPE_BUFFER && \
+ (cpc)->cpc_entry.reg.space_id == \
+ ACPI_ADR_SPACE_SYSTEM_MEMORY)
+
+/* Check if a CPC register is in SystemIo */
+#define CPC_IN_SYSTEM_IO(cpc) ((cpc)->type == ACPI_TYPE_BUFFER && \
+ (cpc)->cpc_entry.reg.space_id == \
+ ACPI_ADR_SPACE_SYSTEM_IO)
+
/* Evaluates to True if reg is a NULL register descriptor */
#define IS_NULL_REG(reg) ((reg)->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY && \
(reg)->address == 0 && \
@@ -1456,6 +1466,9 @@ EXPORT_SYMBOL_GPL(cppc_set_perf);
* transition latency for performance change requests. The closest we have
* is the timing information from the PCCT tables which provides the info
* on the number and frequency of PCC commands the platform can handle.
+ *
+ * If desired_reg is in the SystemMemory or SystemIo ACPI address space,
+ * then assume there is no latency.
*/
unsigned int cppc_get_transition_latency(int cpu_num)
{
@@ -1481,7 +1494,9 @@ unsigned int cppc_get_transition_latency(int cpu_num)
return CPUFREQ_ETERNAL;
desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
- if (!CPC_IN_PCC(desired_reg))
+ if (CPC_IN_SYSTEM_MEMORY(desired_reg) || CPC_IN_SYSTEM_IO(desired_reg))
+ return 0;
+ else if (!CPC_IN_PCC(desired_reg))
return CPUFREQ_ETERNAL;
if (pcc_ss_id < 0)