ACPI / init: Invoke early ACPI initialization later

Commit 73f7d1ca3263 (ACPI / init: Run acpi_early_init() before
timekeeping_init()) optimistically moved the early ACPI initialization
before timekeeping_init(), but that didn't work, because it broke fast
TSC calibration for Julian Wollrath on Thinkpad x121e (and most likely
for others too).  The reason is that acpi_early_init() enables the SCI
and that interferes with the fast TSC calibration mechanism.

Thus follow the original idea to execute acpi_early_init() before
efi_enter_virtual_mode() to help the EFI people for now and we can
revisit the other problem that commit 73f7d1ca3263 attempted to
address in the future (if really necessary).

Fixes: 73f7d1ca3263 (ACPI / init: Run acpi_early_init() before timekeeping_init())
Reported-by: Julian Wollrath <jwollrath@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/init/main.c b/init/main.c
index eb03090..9c7fd4c 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -561,7 +561,6 @@ asmlinkage void __init start_kernel(void)
        init_timers();
        hrtimers_init();
        softirq_init();
-       acpi_early_init();
        timekeeping_init();
        time_init();
        sched_clock_postinit();
@@ -613,6 +612,7 @@ asmlinkage void __init start_kernel(void)
        calibrate_delay();
        pidmap_init();
        anon_vma_init();
+       acpi_early_init();
 #ifdef CONFIG_X86
        if (efi_enabled(EFI_RUNTIME_SERVICES))
                efi_enter_virtual_mode();