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

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Date:   Fri, 15 Dec 2017 23:25:11 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Hanjun Guo <guohanjun@...wei.com>,
        linux-acpi@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v4 4/4] ACPI / 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 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@...ux.intel.com>
---
 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