Revert "ACPI / button: Remove lid_init_state=method mode"

This reverts commit ecb10b694b72ca5ea51b3c90a71ff2a11963425a.

The only expected ACPI control method lid device's usage model is

 1. Listen to the lid notification,
 2. Evaluate _LID after being notified by BIOS,
 3. Suspend the system (if users configure to do so) after seeing "close".

It's not ensured that BIOS will notify OS after boot/resume, and
it's not ensured that BIOS will always generate "open" event upon
opening the lid.

But there are 2 wrong usage models:

 1. When the lid device is responsible for suspend/resume the system,
    userspace requires to see "open" event to be paired with "close" after
    the system is resumed, or it will suspend the system again.

 2. When an external monitor connects to the laptop attached docks,
    userspace requires to see "close" event after the system is resumed so
    that it can determine whether the internal display should remain dark
    and the external display should be lit on.

After we made default kernel behavior to be suitable for usage model 1,
users of usage model 2 start to report regressions for such behavior
change.

Reversion of button.lid_init_state=method doesn't actually reverts to old
default behavior as doing so can enter a regression loop, but facilitates
users to work the reported regressions around with
button.lid_init_state=method.

Fixes: ecb10b694b72 (ACPI / button: Remove lid_init_state=method mode)
Cc: 4.11+ <stable@vger.kernel.org> # 4.11+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=195455
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1430259
Tested-by: Steffen Weber <steffen.weber@gmail.com>
Tested-by: Julian Wiedmann <julian.wiedmann@jwi.name>
Reported-by: Joachim Frieben <jfrieben@hotmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index 668137e4a069..6d5a8c1d3132 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -57,6 +57,7 @@
 
 #define ACPI_BUTTON_LID_INIT_IGNORE     0x00
 #define ACPI_BUTTON_LID_INIT_OPEN       0x01
+#define ACPI_BUTTON_LID_INIT_METHOD     0x02
 
 #define _COMPONENT              ACPI_BUTTON_COMPONENT
 ACPI_MODULE_NAME("button");
@@ -376,6 +377,9 @@ static void acpi_lid_initialize_state(struct acpi_device *device)
         case ACPI_BUTTON_LID_INIT_OPEN:
                 (void)acpi_lid_notify_state(device, 1);
                 break;
+        case ACPI_BUTTON_LID_INIT_METHOD:
+                (void)acpi_lid_update_state(device);
+                break;
         case ACPI_BUTTON_LID_INIT_IGNORE:
         default:
                 break;
@@ -559,6 +563,9 @@ static int param_set_lid_init_state(const char *val, struct kernel_param *kp)
         if (!strncmp(val, "open", sizeof("open") - 1)) {
                 lid_init_state = ACPI_BUTTON_LID_INIT_OPEN;
                 pr_info("Notify initial lid state as open\n");
+        } else if (!strncmp(val, "method", sizeof("method") - 1)) {
+                lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
+                pr_info("Notify initial lid state with _LID return value\n");
         } else if (!strncmp(val, "ignore", sizeof("ignore") - 1)) {
                 lid_init_state = ACPI_BUTTON_LID_INIT_IGNORE;
                 pr_info("Do not notify initial lid state\n");
@@ -572,6 +579,8 @@ static int param_get_lid_init_state(char *buffer, struct kernel_param *kp)
         switch (lid_init_state) {
         case ACPI_BUTTON_LID_INIT_OPEN:
                 return sprintf(buffer, "open");
+        case ACPI_BUTTON_LID_INIT_METHOD:
+                return sprintf(buffer, "method");
         case ACPI_BUTTON_LID_INIT_IGNORE:
                 return sprintf(buffer, "ignore");
         default: