3 files changed, 134 insertions, 6 deletions

diff --git a/kernel/power/console.c b/kernel/power/console.c
index b1dc456474b5..463aa6736751 100644
--- a/kernel/power/console.c
+++ b/kernel/power/console.c
@@ -4,6 +4,7 @@
  * Originally from swsusp.
  */
 
+#include <linux/console.h>
 #include <linux/vt_kern.h>
 #include <linux/kbd_kern.h>
 #include <linux/vt.h>
@@ -14,8 +15,120 @@
 
 static int orig_fgconsole, orig_kmsg;
 
+static DEFINE_MUTEX(vt_switch_mutex);
+
+struct pm_vt_switch {
+	struct list_head head;
+	struct device *dev;
+	bool required;
+};
+
+static LIST_HEAD(pm_vt_switch_list);
+
+
+/**
+ * pm_vt_switch_required - indicate VT switch at suspend requirements
+ * @dev: device
+ * @required: if true, caller needs VT switch at suspend/resume time
+ *
+ * The different console drivers may or may not require VT switches across
+ * suspend/resume, depending on how they handle restoring video state and
+ * what may be running.
+ *
+ * Drivers can indicate support for switchless suspend/resume, which can
+ * save time and flicker, by using this routine and passing 'false' as
+ * the argument.  If any loaded driver needs VT switching, or the
+ * no_console_suspend argument has been passed on the command line, VT
+ * switches will occur.
+ */
+void pm_vt_switch_required(struct device *dev, bool required)
+{
+	struct pm_vt_switch *entry, *tmp;
+
+	mutex_lock(&vt_switch_mutex);
+	list_for_each_entry(tmp, &pm_vt_switch_list, head) {
+		if (tmp->dev == dev) {
+			/* already registered, update requirement */
+			tmp->required = required;
+			goto out;
+		}
+	}
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		goto out;
+
+	entry->required = required;
+	entry->dev = dev;
+
+	list_add(&entry->head, &pm_vt_switch_list);
+out:
+	mutex_unlock(&vt_switch_mutex);
+}
+EXPORT_SYMBOL(pm_vt_switch_required);
+
+/**
+ * pm_vt_switch_unregister - stop tracking a device's VT switching needs
+ * @dev: device
+ *
+ * Remove @dev from the vt switch list.
+ */
+void pm_vt_switch_unregister(struct device *dev)
+{
+	struct pm_vt_switch *tmp;
+
+	mutex_lock(&vt_switch_mutex);
+	list_for_each_entry(tmp, &pm_vt_switch_list, head) {
+		if (tmp->dev == dev) {
+			list_del(&tmp->head);
+			break;
+		}
+	}
+	mutex_unlock(&vt_switch_mutex);
+}
+EXPORT_SYMBOL(pm_vt_switch_unregister);
+
+/*
+ * There are three cases when a VT switch on suspend/resume are required:
+ *   1) no driver has indicated a requirement one way or another, so preserve
+ *      the old behavior
+ *   2) console suspend is disabled, we want to see debug messages across
+ *      suspend/resume
+ *   3) any registered driver indicates it needs a VT switch
+ *
+ * If none of these conditions is present, meaning we have at least one driver
+ * that doesn't need the switch, and none that do, we can avoid it to make
+ * resume look a little prettier (and suspend too, but that's usually hidden,
+ * e.g. when closing the lid on a laptop).
+ */
+static bool pm_vt_switch(void)
+{
+	struct pm_vt_switch *entry;
+	bool ret = true;
+
+	mutex_lock(&vt_switch_mutex);
+	if (list_empty(&pm_vt_switch_list))
+		goto out;
+
+	if (!console_suspend_enabled)
+		goto out;
+
+	list_for_each_entry(entry, &pm_vt_switch_list, head) {
+		if (entry->required)
+			goto out;
+	}
+
+	ret = false;
+out:
+	mutex_unlock(&vt_switch_mutex);
+	return ret;
+}
+
 int pm_prepare_console(void)
 {
+	if (!pm_vt_switch())
+		return 0;
+
 	orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
 	if (orig_fgconsole < 0)
 		return 1;
@@ -26,6 +139,9 @@ int pm_prepare_console(void)
 
 void pm_restore_console(void)
 {
+	if (!pm_vt_switch())
+		return;
+
 	if (orig_fgconsole >= 0) {
 		vt_move_to_console(orig_fgconsole, 0);
 		vt_kmsg_redirect(orig_kmsg);
diff --git a/kernel/power/poweroff.c b/kernel/power/poweroff.c
index 68197a4e8fc9..7ef6866b521d 100644
--- a/kernel/power/poweroff.c
+++ b/kernel/power/poweroff.c
@@ -32,7 +32,7 @@ static void handle_poweroff(int key)
 
 static struct sysrq_key_op	sysrq_poweroff_op = {
 	.handler        = handle_poweroff,
-	.help_msg       = "powerOff",
+	.help_msg       = "poweroff(o)",
 	.action_msg     = "Power Off",
 	.enable_mask	= SYSRQ_ENABLE_BOOT,
 };
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index d4feda084a3a..bef86d121eb2 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -76,8 +76,20 @@ EXPORT_SYMBOL_GPL(suspend_set_ops);
 
 bool valid_state(suspend_state_t state)
 {
-	if (state == PM_SUSPEND_FREEZE)
-		return true;
+	if (state == PM_SUSPEND_FREEZE) {
+#ifdef CONFIG_PM_DEBUG
+		if (pm_test_level != TEST_NONE &&
+		    pm_test_level != TEST_FREEZER &&
+		    pm_test_level != TEST_DEVICES &&
+		    pm_test_level != TEST_PLATFORM) {
+			printk(KERN_WARNING "Unsupported pm_test mode for "
+					"freeze state, please choose "
+					"none/freezer/devices/platform.\n");
+			return false;
+		}
+#endif
+			return true;
+	}
 	/*
 	 * PM_SUSPEND_STANDBY and PM_SUSPEND_MEMORY states need lowlevel
 	 * support and need to be valid to the lowlevel
@@ -184,6 +196,9 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
 			goto Platform_wake;
 	}
 
+	if (suspend_test(TEST_PLATFORM))
+		goto Platform_wake;
+
 	/*
 	 * PM_SUSPEND_FREEZE equals
 	 * frozen processes + suspended devices + idle processors.
@@ -195,9 +210,6 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
 		goto Platform_wake;
 	}
 
-	if (suspend_test(TEST_PLATFORM))
-		goto Platform_wake;
-
 	error = disable_nonboot_cpus();
 	if (error || suspend_test(TEST_CPUS))
 		goto Enable_cpus;