diff --git a/drivers/acpi/acpica/exfield.c b/drivers/acpi/acpica/exfield.c
index 9a55524ed8f4..50317fe0cbd5 100644
--- a/drivers/acpi/acpica/exfield.c
+++ b/drivers/acpi/acpica/exfield.c
@@ -45,12 +45,13 @@ static const u8 acpi_protocol_lengths[] = {
 
 /*
  * The following macros determine a given offset is a COMD field.
- * According to the specification, generic subspaces (types 0-2) contains a
- * 2-byte COMD field at offset 4 and master subspaces (type 3) contains a 4-byte
- * COMD field starting at offset 12.
+ * According to the specification, the PCC OperationRegion begins after
+ * the PCC signature. The raw shared memory COMD offsets of 4 for generic
+ * subspaces (types 0-2) and 12 for master subspaces (type 3) therefore
+ * appear at OperationRegion offsets 0 and 8.
  */
-#define GENERIC_SUBSPACE_COMMAND(a)     (4 == a || a == 5)
-#define MASTER_SUBSPACE_COMMAND(a)      (12 <= a && a <= 15)
+#define GENERIC_SUBSPACE_COMMAND(a)     (0 == a || a == 1)
+#define MASTER_SUBSPACE_COMMAND(a)      (8 <= a && a <= 11)
 
 /*******************************************************************************
  *