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-rw-r--r--drivers/acpi/executer/exprep.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/drivers/acpi/executer/exprep.c b/drivers/acpi/executer/exprep.c
index 7719ae5d4f1..916234bf811 100644
--- a/drivers/acpi/executer/exprep.c
+++ b/drivers/acpi/executer/exprep.c
@@ -519,13 +519,20 @@ acpi_status acpi_ex_prep_field_value(struct acpi_create_field_info *info)
acpi_ut_add_reference(obj_desc->index_field.index_obj);
/*
+ * February 2006: Changed to match MS behavior
+ *
* The value written to the Index register is the byte offset of the
- * target field
- * Note: may change code to: ACPI_DIV_8 (Info->field_bit_position)
+ * target field.
+ *
+ * Previously, the value was calculated as an index in terms of the
+ * width of the Data register, as below:
+ *
+ * obj_desc->index_field.Value = (u32)
+ * (Info->field_bit_position / ACPI_MUL_8 (
+ * obj_desc->Field.access_byte_width));
*/
- obj_desc->index_field.value = (u32)
- (info->field_bit_position /
- ACPI_MUL_8(obj_desc->field.access_byte_width));
+ obj_desc->index_field.value =
+ (u32) ACPI_DIV_8(info->field_bit_position);
ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
"index_field: bit_off %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",