ACPI hibernate: Introduce new kernel parameter acpi_sleep=s4_nonvs

On some machines it may be necessary to disable the saving/restoring
of the ACPI NVS memory region during hibernation/resume.  For this
purpose, introduce new ACPI kernel command line option
acpi_sleep=s4_nonvs.

Based on a patch by Zhang Rui.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@tuxonice.net>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c
index 45a8015e4217..bef41fd4c877 100644
--- a/drivers/acpi/sleep/main.c
+++ b/drivers/acpi/sleep/main.c
@@ -101,6 +101,19 @@ void __init acpi_old_suspend_ordering(void)
  * cases.
  */
 static bool set_sci_en_on_resume;
+/*
+ * The ACPI specification wants us to save NVS memory regions during hibernation
+ * and to restore them during the subsequent resume.  However, it is not certain
+ * if this mechanism is going to work on all machines, so we allow the user to
+ * disable this mechanism using the 'acpi_sleep=s4_nonvs' kernel command line
+ * option.
+ */
+static bool s4_no_nvs;
+
+void __init acpi_s4_no_nvs(void)
+{
+        s4_no_nvs = true;
+}
 
 /**
  *      acpi_pm_disable_gpes - Disable the GPEs.
@@ -396,7 +409,7 @@ static int acpi_hibernation_begin(void)
 {
         int error;
 
-        error = hibernate_nvs_alloc();
+        error = s4_no_nvs ? 0 : hibernate_nvs_alloc();
         if (!error) {
                 acpi_target_sleep_state = ACPI_STATE_S4;
                 acpi_sleep_tts_switch(acpi_target_sleep_state);
@@ -494,7 +507,8 @@ static int acpi_hibernation_begin_old(void)
         error = acpi_sleep_prepare(ACPI_STATE_S4);
 
         if (!error) {
-                error = hibernate_nvs_alloc();
+                if (!s4_no_nvs)
+                        error = hibernate_nvs_alloc();
                 if (!error)
                         acpi_target_sleep_state = ACPI_STATE_S4;
         }