ACPI: introduce kernel parameter acpi_sleep=sci_force_enable

Introduce kernel parameter acpi_sleep=sci_force_enable

some laptop requires SCI_EN being set directly on resume,
or else they hung somewhere in the resume code path.

We already have a blacklist for these laptops but we still need
this option, especially when debugging some suspend/resume problems,
in case there are systems that need this workaround and are not yet
in the blacklist.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 5f2c379ab7bf..79d33d908b5a 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -81,6 +81,23 @@ static int acpi_sleep_prepare(u32 acpi_state)
 #ifdef CONFIG_ACPI_SLEEP
 static u32 acpi_target_sleep_state = ACPI_STATE_S0;
 /*
+ * According to the ACPI specification the BIOS should make sure that ACPI is
+ * enabled and SCI_EN bit is set on wake-up from S1 - S3 sleep states.  Still,
+ * some BIOSes don't do that and therefore we use acpi_enable() to enable ACPI
+ * on such systems during resume.  Unfortunately that doesn't help in
+ * particularly pathological cases in which SCI_EN has to be set directly on
+ * resume, although the specification states very clearly that this flag is
+ * owned by the hardware.  The set_sci_en_on_resume variable will be set in such
+ * cases.
+ */
+static bool set_sci_en_on_resume;
+
+void __init acpi_set_sci_en_on_resume(void)
+{
+        set_sci_en_on_resume = 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.
@@ -170,18 +187,6 @@ static void acpi_pm_end(void)
 #endif /* CONFIG_ACPI_SLEEP */
 
 #ifdef CONFIG_SUSPEND
-/*
- * According to the ACPI specification the BIOS should make sure that ACPI is
- * enabled and SCI_EN bit is set on wake-up from S1 - S3 sleep states.  Still,
- * some BIOSes don't do that and therefore we use acpi_enable() to enable ACPI
- * on such systems during resume.  Unfortunately that doesn't help in
- * particularly pathological cases in which SCI_EN has to be set directly on
- * resume, although the specification states very clearly that this flag is
- * owned by the hardware.  The set_sci_en_on_resume variable will be set in such
- * cases.
- */
-static bool set_sci_en_on_resume;
-
 extern void do_suspend_lowlevel(void);
 
 static u32 acpi_suspend_states[] = {