Revert "ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism"

This reverts commit 8fd145917fb62368a9b80db59562c20576238f5a.

http://bugzilla.kernel.org/show_bug.cgi?id=11942

Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/reboot.c

@@ -15,28 +15,9 @@ void acpi_reboot(void)
 
 	rr = &acpi_gbl_FADT.reset_register;
 
-	/*
-	 * Is the ACPI reset register supported?
-	 *
-	 * According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates
-	 * whether the ACPI reset mechanism is supported.
-	 *
-	 * However, some boxes have this bit clear, yet a valid
-	 * ACPI_RESET_REG & RESET_VALUE, and ACPI reboot is the only
-	 * mechanism that works for them after S3.
-	 *
-	 * This suggests that other operating systems may not be checking
-	 * the RESET_REG_SUP bit, and are using other means to decide
-	 * whether to use the ACPI reboot mechanism or not.
-	 *
-	 * So when acpi reboot is requested,
-	 * only the reset_register is checked. If the following
-	 * conditions are met, it indicates that the reset register is supported.
-	 * 	a. reset_register is not zero
-	 * 	b. the access width is eight
-	 * 	c. the bit_offset is zero
-	 */
-	if (!(rr->address) || rr->bit_width != 8 || rr->bit_offset != 0)
+	/* Is the reset register supported? */
+	if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER) ||
+	    rr->bit_width != 8 || rr->bit_offset != 0)
 		return;
 
 	reset_value = acpi_gbl_FADT.reset_value;