ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism

ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism

commit 8fd145917fb62368a9b80db59562c20576238f5a upstream

ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism

According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates
whether the ACPI reboot mechanism is supported.

However, some boxes have this bit clear, have 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.

Here we stop checking RESET_REG_SUP.
Instead, 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

http://bugzilla.kernel.org/show_bug.cgi?id=7299
http://bugzilla.kernel.org/show_bug.cgi?id=1148

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>