ACPI / x86: boot: Don't setup SCI on HW-reduced platforms

As per note in 5.2.9 Fixed ACPI Description Table (FADT) chapter of ACPI
specification, on HW-reduced platforma OSPM should 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 a HW-reduced platform.

HW-reduced platforms will still be able to use SCI in case it provides
an override record in MADT table.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 5a12cadbf019..4bf004bab4b2 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1209,8 +1209,9 @@ 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);