[PATCH 3/5] ACPI: Add fixups for AMD P-state figures

[Matthew Garrett]

Some AMD systems may round the frequencies in ACPI tables to 100MHz
boundaries. We can obtain the real frequencies from MSRs, so add a quirk
to fix these frequencies up on AMD systems.

Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
---
 drivers/acpi/processor_perflib.c |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 3a73a93..6c7d49d 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -306,6 +306,34 @@ static int acpi_processor_get_performance_control(struct acpi_processor *pr)
 	return result;
 }
 
+#ifdef CONFIG_X86
+/*
+ * Some AMDs have 50MHz frequency multiples, but only provide 100MHz rounding
+ * in their ACPI data. Calculate the real values and fix up the _PSS data.
+ */
+static void amd_fixup_frequency(struct acpi_processor_px *px, int i)
+{
+	u32 hi, lo, fid, did;
+	int index = px->control & 0x00000007;
+
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+		return;
+
+	if ((boot_cpu_data.x86 == 0x10 && boot_cpu_data.x86_model < 10)
+	    || boot_cpu_data.x86 == 0x11) {
+		rdmsr(0xc0010064 + index, lo, hi);
+		fid = lo & 0x3f;
+		did = (lo >> 6) & 7;
+		if (boot_cpu_data.x86 == 0x10)
+			px->core_frequency = (100 * (fid + 0x10)) >> did;
+		else
+			px->core_frequency = (100 * (fid + 8)) >> did;
+	}
+}
+#else
+static void amd_fixup_frequency(struct acpi_processor_px *px, int i) {};
+#endif
+
 static int acpi_processor_get_performance_states(struct acpi_processor *pr)
 {
 	int result = 0;
@@ -360,6 +388,8 @@ static int acpi_processor_get_performance_states(struct acpi_processor *pr)
 			goto end;
 		}
 
+		amd_fixup_frequency(px, i);
+
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 				  "State [%d]: core_frequency[%d] power[%d] transition_latency[%d] bus_master_latency[%d] control[0x%x] status[0x%x]\n",
 				  i,
-- 
1.7.5

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