[PATCH v6 4/6] ACPI: in HW reduced mode, using FADT PM information is not allowed.

[al.stone at linaro.org]

From: Al Stone <al.stone at linaro.org>

Per the ACPI 5.0 specification, section 5.2.9, none of the power
management fields in the FADT are to be used.  Short-circuit using
any of those fields in acpi_processor_get_power_info_fadt().

Signed-off-by: Al Stone <al.stone at linaro.org>
---
 drivers/acpi/processor_idle.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index eac984a..89f0a0f 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -270,6 +270,14 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
 	if (!pr->pblk)
 		return -ENODEV;
 
+	/*
+	 * Using power management information from the FADT is not
+	 * allowed when in HW reduced mode.  See ACPI 5.0, section
+	 * 5.2.9.
+	 */
+	if (acpi_gbl_reduced_hardware)
+		return -ENODEV;
+
 	/* if info is obtained from pblk/fadt, type equals state */
 	pr->power.states[ACPI_STATE_C2].type = ACPI_STATE_C2;
 	pr->power.states[ACPI_STATE_C3].type = ACPI_STATE_C3;
-- 
1.8.4.2