ACPI / Sleep: Allow the NVS saving to be skipped during suspend to RAM

Commit 2a6b69765ad794389f2fc3e14a0afa1a995221c2
(ACPI: Store NVS state even when entering suspend to RAM) caused the
ACPI suspend code save the NVS area during suspend and restore it
during resume unconditionally, although it is known that some systems
need to use acpi_sleep=s4_nonvs for hibernation to work.  To allow
the affected systems to avoid saving and restoring the NVS area
during suspend to RAM and resume, introduce kernel command line
option acpi_sleep=nonvs and make acpi_sleep=s4_nonvs work as its
alias temporarily (add acpi_sleep=s4_nonvs to the feature removal
file).

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=16396 .

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-and-tested-by: tomas m <tmezzadra@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 17 insertions, 18 deletions

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 5b7c52e4a00f..2862c781b372 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -82,6 +82,20 @@ static int acpi_sleep_prepare(u32 acpi_state)
 static u32 acpi_target_sleep_state = ACPI_STATE_S0;
 
 /*
+ * The ACPI specification wants us to save NVS memory regions during hibernation
+ * and to restore them during the subsequent resume.  Windows does that also for
+ * suspend to RAM.  However, it is known that this mechanism does not work on
+ * all machines, so we allow the user to disable it with the help of the
+ * 'acpi_sleep=nonvs' kernel command line option.
+ */
+static bool nvs_nosave;
+
+void __init acpi_nvs_nosave(void)
+{
+        nvs_nosave = true;
+}
+
+/*
  * ACPI 1.0 wants us to execute _PTS before suspending devices, so we allow the
  * user to request that behavior by using the 'acpi_old_suspend_ordering'
  * kernel command line option that causes the following variable to be set.
@@ -197,8 +211,7 @@ static int acpi_suspend_begin(suspend_state_t pm_state)
         u32 acpi_state = acpi_suspend_states[pm_state];
         int error = 0;
 
-        error = suspend_nvs_alloc();
-
+        error = nvs_nosave ? 0 : suspend_nvs_alloc();
         if (error)
                 return error;
 
@@ -388,20 +401,6 @@ static struct dmi_system_id __initdata acpisleep_dmi_table[] = {
 #endif /* CONFIG_SUSPEND */
 
 #ifdef CONFIG_HIBERNATION
-/*
- * 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;
-}
-
 static unsigned long s4_hardware_signature;
 static struct acpi_table_facs *facs;
 static bool nosigcheck;
@@ -415,7 +414,7 @@ static int acpi_hibernation_begin(void)
 {
         int error;
 
-        error = s4_no_nvs ? 0 : suspend_nvs_alloc();
+        error = nvs_nosave ? 0 : suspend_nvs_alloc();
         if (!error) {
                 acpi_target_sleep_state = ACPI_STATE_S4;
                 acpi_sleep_tts_switch(acpi_target_sleep_state);
@@ -510,7 +509,7 @@ static int acpi_hibernation_begin_old(void)
         error = acpi_sleep_prepare(ACPI_STATE_S4);
 
         if (!error) {
-                if (!s4_no_nvs)
+                if (!nvs_nosave)
                         error = suspend_nvs_alloc();
                 if (!error)
                         acpi_target_sleep_state = ACPI_STATE_S4;