ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism (8fd14591) · Commits · 戴 / test

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>

drivers/acpi/reboot.c

+22 −3

Original line number	Diff line number	Diff line
		@@ -15,9 +15,28 @@ void acpi_reboot(void)

		rr = &acpi_gbl_FADT.reset_register;

		/* Is the reset register supported? */
		if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER) \|\|
		rr->bit_width != 8 \|\| rr->bit_offset != 0)
		/*
		* 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)
		return;

		reset_value = acpi_gbl_FADT.reset_value;

Admin message