Message-Id: <9789954a4ce9d4bef1a6b7947015123a9e2691d8.1496828498.git.lv.zheng@intel.com>
Date:   Wed,  7 Jun 2017 17:43:45 +0800
From:   Lv Zheng <lv.zheng@...el.com>
To:     "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>
Cc:     Lv Zheng <lv.zheng@...el.com>, Lv Zheng <zetalog@...il.com>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        systemd-devel@...ts.freedesktop.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Peter Hutterer <peter.hutterer@...-t.net>
Subject: [RFC PATCH v5 2/2] ACPI: button: Add a quirk mode for Surface Pro 1 like laptop

Some platforms never send "open" events, _LID returns value sticks to
"close", ex., Surface Pro 1.

Such platforms cannot work well with systemd 229 in
button.lid_init_state=method mode, but button.lid_init_state=open
workaround is available for them to work with systemd 229 and they can work
perfectly with systemd 233 in button.lid_init_state=ignore mode.

This patch introduces a boot parameter to mark such platform lid device as
unreliable to replace old button.lid_init_state=ignore mode. So that users
can use this quirk to make such platforms working with systemd 233. Since
such platform only sends "close", old complicated "open" complement event
mechanism is replaced by a simpler one of always prepending "open" before
any events.

Cc: <systemd-devel@...ts.freedesktop.org>
Cc: Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc: Peter Hutterer <peter.hutterer@...-t.net>
Signed-off-by: Lv Zheng <lv.zheng@...el.com>
---
 drivers/acpi/button.c | 164 ++++++++++++++++++++------------------------------
 1 file changed, 66 insertions(+), 98 deletions(-)

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index fd8eff6..02b85c1 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -56,9 +56,8 @@
 #define ACPI_BUTTON_DEVICE_NAME_LID	"Lid Switch"
 #define ACPI_BUTTON_TYPE_LID		0x05
 
-#define ACPI_BUTTON_LID_INIT_IGNORE	0x00
+#define ACPI_BUTTON_LID_INIT_METHOD	0x00
 #define ACPI_BUTTON_LID_INIT_OPEN	0x01
-#define ACPI_BUTTON_LID_INIT_METHOD	0x02
 
 #define _COMPONENT		ACPI_BUTTON_COMPONENT
 ACPI_MODULE_NAME("button");
@@ -109,23 +108,20 @@ struct acpi_button {
 	struct timer_list lid_timer;
 	char phys[32];			/* for input device */
 	unsigned long pushed;
-	int last_state;
-	ktime_t last_time;
 	bool suspended;
 };
 
+static DEFINE_MUTEX(lid_device_lock);
 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");
-
 static unsigned long lid_update_interval __read_mostly = 10 * MSEC_PER_SEC;
 module_param(lid_update_interval, ulong, 0644);
 MODULE_PARM_DESC(lid_update_interval, "Interval (ms) between lid state updates");
 
+static bool lid_unreliable __read_mostly = false;
+
 /* --------------------------------------------------------------------------
                               FS Interface (/proc)
    -------------------------------------------------------------------------- */
@@ -149,79 +145,12 @@ 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");
 
-		/*
-		 * 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 (lid_unreliable)
+		input_report_switch(button->input, SW_LID, 0);
+
+	input_report_switch(button->input, SW_LID, !state);
+	input_sync(button->input);
 
 	if (state)
 		pm_wakeup_event(&device->dev, 0);
@@ -382,22 +311,25 @@ static void acpi_lid_tick(struct acpi_device *device)
 {
 	struct acpi_button *button = acpi_driver_data(device);
 
-	mod_timer(&button->lid_timer,
-		  jiffies + msecs_to_jiffies(lid_update_interval));
+	if (!lid_unreliable)
+		mod_timer(&button->lid_timer,
+			  jiffies + msecs_to_jiffies(lid_update_interval));
 }
 
 static void acpi_lid_timeout(ulong arg)
 {
 	struct acpi_device *device = (struct acpi_device *)arg;
 
-	switch (lid_init_state) {
-	case ACPI_BUTTON_LID_INIT_OPEN:
-		(void)acpi_lid_notify_state(device, 1);
-		break;
-	case ACPI_BUTTON_LID_INIT_METHOD:
-		acpi_lid_update_state(device);
-		acpi_lid_tick(device);
-		break;
+	if (!lid_unreliable) {
+		switch (lid_init_state) {
+		case ACPI_BUTTON_LID_INIT_OPEN:
+			(void)acpi_lid_notify_state(device, 1);
+			break;
+		case ACPI_BUTTON_LID_INIT_METHOD:
+			acpi_lid_update_state(device);
+			acpi_lid_tick(device);
+			break;
+		}
 	}
 }
 
@@ -506,8 +438,6 @@ 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();
 		setup_timer(&button->lid_timer,
 			    acpi_lid_timeout, (ulong)device);
 	} else {
@@ -551,7 +481,10 @@ static int acpi_button_add(struct acpi_device *device)
 		 * This assumes there's only one lid device, or if there are
 		 * more we only care about the last one...
 		 */
+		mutex_lock(&lid_device_lock);
+		get_device(&device->dev);
 		lid_device = device;
+		mutex_unlock(&lid_device_lock);
 	}
 
 	printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
@@ -570,8 +503,15 @@ static int acpi_button_remove(struct acpi_device *device)
 {
 	struct acpi_button *button = acpi_driver_data(device);
 
-	if (button->type == ACPI_BUTTON_TYPE_LID)
+	if (button->type == ACPI_BUTTON_TYPE_LID) {
 		del_timer(&button->lid_timer);
+		mutex_lock(&lid_device_lock);
+		if (device == lid_device) {
+			put_device(&device->dev);
+			lid_device = NULL;
+		}
+		mutex_unlock(&lid_device_lock);
+	}
 	acpi_button_remove_fs(device);
 	input_unregister_device(button->input);
 	kfree(button);
@@ -588,9 +528,6 @@ static int param_set_lid_init_state(const char *val, struct kernel_param *kp)
 	} 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");
 	} else
 		result = -EINVAL;
 	return result;
@@ -603,17 +540,48 @@ static int param_get_lid_init_state(char *buffer, struct kernel_param *kp)
 		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:
 		return sprintf(buffer, "invalid");
 	}
 	return 0;
 }
 
+static int param_set_lid_unreliable(const char *val, struct kernel_param *kp)
+{
+	int result = 0;
+	struct device *dev;
+	struct acpi_device *device;
+	struct acpi_button *button;
+
+	result = param_set_bool(val, kp);
+	if (result)
+		return result;
+
+	mutex_lock(&lid_device_lock);
+	if (lid_device) {
+		dev = get_device(&lid_device->dev);
+		mutex_unlock(&lid_device_lock);
+		device = to_acpi_device(dev);
+		button = acpi_driver_data(device);
+		if (lid_unreliable)
+			del_timer(&button->lid_timer);
+		else
+			acpi_lid_tick(device);
+		put_device(&device->dev);
+		mutex_lock(&lid_device_lock);
+	}
+	mutex_unlock(&lid_device_lock);
+	return result;
+}
+
 module_param_call(lid_init_state,
 		  param_set_lid_init_state, param_get_lid_init_state,
 		  NULL, 0644);
 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
 
+module_param_call(lid_unreliable,
+		 param_set_lid_unreliable, param_get_bool,
+		 &lid_unreliable, 0644);
+MODULE_PARM_DESC(lid_unreliable, "Mark lid device as unreliable");
+
 module_acpi_driver(acpi_button_driver);
-- 
2.7.4

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