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, 4 insertions, 1 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ba4d9dff113..736d45602886 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -240,7 +240,7 @@ and is between 256 and 4096 characters. It is defined in the file
 
         acpi_sleep=     [HW,ACPI] Sleep options
                         Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
-                                  old_ordering, s4_nonvs }
+                                  old_ordering, s4_nonvs, sci_force_enable }
                         See Documentation/power/video.txt for information on
                         s3_bios and s3_mode.
                         s3_beep is for debugging; it makes the PC's speaker beep
@@ -253,6 +253,9 @@ and is between 256 and 4096 characters. It is defined in the file
                         of _PTS is used by default).
                         s4_nonvs prevents the kernel from saving/restoring the
                         ACPI NVS memory during hibernation.
+                        sci_force_enable causes the kernel to set SCI_EN directly
+                        on resume from S1/S3 (which is against the ACPI spec,
+                        but some broken systems don't work without it).
 
         acpi_use_timer_override [HW,ACPI]
                         Use timer override. For some broken Nvidia NF5 boards