[PATCH v4 4/4] ACPI / boot: Don't setup SCI on HW reduced platforms

[Andy Shevchenko]

As per note in 5.2.9 Fixed ACPI Description Table (FADT) chapter of ACPI
specification OSPM will ignore fields related to the ACPI HW register
interface, one of which is SCI_INT.

Follow the spec and ignore any configuration done for interrupt line
defined by SCI_INT if FADT specifies HW reduced platform.

HW reduced platform would be still able to use SCI in case it provides
an override record in MADT table.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/acpi/boot.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 6302a931fe9b..290b6f5a2d50 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1212,8 +1212,9 @@ static int __init acpi_parse_madt_ioapic_entries(void)
 	/*
 	 * If BIOS did not supply an INT_SRC_OVR for the SCI
 	 * pretend we got one so we can set the SCI flags.
+	 * But ignore setting up SCI on hardware reduced platforms.
 	 */
-	if (acpi_sci_override_gsi == INVALID_ACPI_IRQ)
+	if (acpi_sci_override_gsi == INVALID_ACPI_IRQ && !acpi_gbl_reduced_hardware)
 		acpi_sci_ioapic_setup(acpi_gbl_FADT.sci_interrupt, 0, 0,
 				      acpi_gbl_FADT.sci_interrupt);
 
-- 
2.15.1