- acpi_ut_add_reference (obj_desc->index_field.data_obj);
- acpi_ut_add_reference (obj_desc->index_field.index_obj);
-
- ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
- "index_field: bit_off %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",
- obj_desc->index_field.start_field_bit_offset,
- obj_desc->index_field.base_byte_offset,
- obj_desc->index_field.value,
- obj_desc->field.access_byte_width,
- obj_desc->index_field.index_obj,
- obj_desc->index_field.data_obj));
+ acpi_ut_add_reference(obj_desc->index_field.data_obj);
+ acpi_ut_add_reference(obj_desc->index_field.index_obj);
+
+ /*
+ * April 2006: Changed to match MS behavior
+ *
+ * The value written to the Index register is the byte offset of the
+ * target field in units of the granularity of the index_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));
+ *
+ * February 2006: Tried value as a byte offset:
+ * obj_desc->index_field.Value = (u32)
+ * ACPI_DIV_8 (Info->field_bit_position);
+ */
+ obj_desc->index_field.value =
+ (u32) ACPI_ROUND_DOWN(ACPI_DIV_8(info->field_bit_position),
+ obj_desc->index_field.
+ access_byte_width);
+
+ ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
+ "IndexField: BitOff %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",
+ obj_desc->index_field.start_field_bit_offset,
+ obj_desc->index_field.base_byte_offset,
+ obj_desc->index_field.value,
+ obj_desc->field.access_byte_width,
+ obj_desc->index_field.index_obj,
+ obj_desc->index_field.data_obj));