From 382fabb2974a153de73949e4bbd033c3235dac76 Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Fri, 21 Jul 2017 22:32:06 +0300
Subject: x86: acpi: Don't touch hardware on HW reduced platforms

If ACPI HW reduced bit in FADT is set we should ignore any ACPI hardware
communications.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/arch/x86/lib/acpi_table.c b/arch/x86/lib/acpi_table.c
index da6014f..3eb1011 100644
--- a/arch/x86/lib/acpi_table.c
+++ b/arch/x86/lib/acpi_table.c
@@ -463,6 +463,10 @@ ulong write_acpi_tables(ulong start)
 
 	debug("ACPI: done\n");
 
+	/* Don't touch ACPI hardware on HW reduced platforms */
+	if (fadt->flags & ACPI_FADT_HW_REDUCED_ACPI)
+		return current;
+
 	/*
 	 * Other than waiting for OSPM to request us to switch to ACPI mode,
 	 * do it by ourselves, since SMI will not be triggered.
-- 
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