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 da6014fb415699dde4ee8cc4d5bba3893eaa22a5..3eb101105b8228ef5f0cea744ee3f55012a27142 100644 (file)
--- 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.