1 files changed, 82 insertions, 3 deletions

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index 31abb0bdd4f2..e19f530f1083 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -19,6 +19,8 @@
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
 
+#define pr_fmt(fmt) "ACPI : button: " fmt
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -104,6 +106,8 @@ struct acpi_button {
         struct input_dev *input;
         char phys[32];                  /* for input device */
         unsigned long pushed;
+        int last_state;
+        ktime_t last_time;
         bool suspended;
 };
 
@@ -111,6 +115,10 @@ static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
 static struct acpi_device *lid_device;
 static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
 
+static unsigned long lid_report_interval __read_mostly = 500;
+module_param(lid_report_interval, ulong, 0644);
+MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
+
 /* --------------------------------------------------------------------------
                               FS Interface (/proc)
    -------------------------------------------------------------------------- */
@@ -134,10 +142,79 @@ static int acpi_lid_notify_state(struct acpi_device *device, int state)
 {
         struct acpi_button *button = acpi_driver_data(device);
         int ret;
+        ktime_t next_report;
+        bool do_update;
+
+        /*
+         * In lid_init_state=ignore mode, if user opens/closes lid
+         * frequently with "open" missing, and "last_time" is also updated
+         * frequently, "close" cannot be delivered to the userspace.
+         * So "last_time" is only updated after a timeout or an actual
+         * switch.
+         */
+        if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
+            button->last_state != !!state)
+                do_update = true;
+        else
+                do_update = false;
+
+        next_report = ktime_add(button->last_time,
+                                ms_to_ktime(lid_report_interval));
+        if (button->last_state == !!state &&
+            ktime_after(ktime_get(), next_report)) {
+                /* Complain the buggy firmware */
+                pr_warn_once("The lid device is not compliant to SW_LID.\n");
 
-        /* input layer checks if event is redundant */
-        input_report_switch(button->input, SW_LID, !state);
-        input_sync(button->input);
+                /*
+                 * Send the unreliable complement switch event:
+                 *
+                 * On most platforms, the lid device is reliable. However
+                 * there are exceptions:
+                 * 1. Platforms returning initial lid state as "close" by
+                 *    default after booting/resuming:
+                 *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
+                 *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
+                 * 2. Platforms never reporting "open" events:
+                 *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
+                 * On these buggy platforms, the usage model of the ACPI
+                 * lid device actually is:
+                 * 1. The initial returning value of _LID may not be
+                 *    reliable.
+                 * 2. The open event may not be reliable.
+                 * 3. The close event is reliable.
+                 *
+                 * But SW_LID is typed as input switch event, the input
+                 * layer checks if the event is redundant. Hence if the
+                 * state is not switched, the userspace cannot see this
+                 * platform triggered reliable event. By inserting a
+                 * complement switch event, it then is guaranteed that the
+                 * platform triggered reliable one can always be seen by
+                 * the userspace.
+                 */
+                if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
+                        do_update = true;
+                        /*
+                         * Do generate complement switch event for "close"
+                         * as "close" is reliable and wrong "open" won't
+                         * trigger unexpected behaviors.
+                         * Do not generate complement switch event for
+                         * "open" as "open" is not reliable and wrong
+                         * "close" will trigger unexpected behaviors.
+                         */
+                        if (!state) {
+                                input_report_switch(button->input,
+                                                    SW_LID, state);
+                                input_sync(button->input);
+                        }
+                }
+        }
+        /* Send the platform triggered reliable event */
+        if (do_update) {
+                input_report_switch(button->input, SW_LID, !state);
+                input_sync(button->input);
+                button->last_state = !!state;
+                button->last_time = ktime_get();
+        }
 
         if (state)
                 pm_wakeup_event(&device->dev, 0);
@@ -411,6 +488,8 @@ static int acpi_button_add(struct acpi_device *device)
                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
                 sprintf(class, "%s/%s",
                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
+                button->last_state = !!acpi_lid_evaluate_state(device);
+                button->last_time = ktime_get();
         } else {
                 printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
                 error = -ENODEV;