commit cd8f863a804d9388b09771640110577dddafc695
Author: Stefan Demharter <stefan.demharter@gmx.net>
Date:   Thu Oct 24 00:06:09 2013 +0200

    vgaswitcheroo: restore mux and power states after resume from hibernation.

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index ec0ae2d..4731f02 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -28,6 +28,7 @@
 #include <linux/console.h>
 #include <linux/vga_switcheroo.h>
 #include <linux/pm_runtime.h>
+#include <linux/suspend.h>
 
 #include <linux/vgaarb.h>
 
@@ -72,6 +73,46 @@ static struct vgasr_priv vgasr_priv = {
 	.clients = LIST_HEAD_INIT(vgasr_priv.clients),
 };
 
+/* save state of mux to restore it upon hibernation resume */
+// Assume initial state after boot: mux is set to IGD
+#define MUX_POWER_ON_STATE VGA_SWITCHEROO_IGD
+static int mux_id = MUX_POWER_ON_STATE;
+
+static int vga_switchoff(struct vga_switcheroo_client *client);
+
+static int vga_resume(struct notifier_block *nb,
+                                unsigned long val, void *ign)
+{
+	int ret = 0;
+	struct vga_switcheroo_client *client;
+	pr_info("vga_switcheroo: vga_resume %d %d %d\n", (int)val, PM_POST_HIBERNATION, mux_id);
+	if (val != PM_POST_HIBERNATION) return 0;
+	if (mux_id != VGA_SWITCHEROO_IGD) {
+		mutex_lock(&vgasr_mutex);
+		pr_info("vga_switcheroo: restoring switch to %d after hibernate\n", mux_id);
+		// Restore mux state
+		if (mux_id != MUX_POWER_ON_STATE)
+			ret = vgasr_priv.handler->switchto(mux_id);
+		// Restore power state
+		// Assumes all gpus have power after boot
+		list_for_each_entry(client, &vgasr_priv.clients, list) {
+			if (!client->pwr_state) {
+				// Device was powered off, so we redo that...
+				pr_info("vga_switcheroo: restoring power off of device %d after hibernate\n", client->id);
+				vga_switchoff(client);
+			}
+		}
+		mutex_unlock(&vgasr_mutex);
+		if (ret) pr_warn("vga_switcheroo: failed\n");
+	}
+	return 0;
+}
+
+static struct notifier_block vga_pm_nb = {
+	.notifier_call = vga_resume,
+	.priority = 0,
+};
+
 static bool vga_switcheroo_ready(void)
 {
 	/* we're ready if we get two clients + handler */
@@ -83,6 +124,7 @@ static void vga_switcheroo_enable(void)
 {
 	int ret;
 	struct vga_switcheroo_client *client;
+	register_pm_notifier(&vga_pm_nb);
 
 	/* call the handler to init */
 	if (vgasr_priv.handler->init)
@@ -119,14 +161,21 @@ int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
 }
 EXPORT_SYMBOL(vga_switcheroo_register_handler);
 
+// vgasr_mutex has to be locked from caller
+void vga_switcheroo_disable(void)
+{
+	unregister_pm_notifier(&vga_pm_nb);
+	pr_info("vga_switcheroo: disabled\n");
+	vga_switcheroo_debugfs_fini(&vgasr_priv);
+	vgasr_priv.active = false;
+}
+
 void vga_switcheroo_unregister_handler(void)
 {
 	mutex_lock(&vgasr_mutex);
 	vgasr_priv.handler = NULL;
 	if (vgasr_priv.active) {
-		pr_info("vga_switcheroo: disabled\n");
-		vga_switcheroo_debugfs_fini(&vgasr_priv);
-		vgasr_priv.active = false;
+		vga_switcheroo_disable();
 	}
 	mutex_unlock(&vgasr_mutex);
 }
@@ -235,9 +284,7 @@ void vga_switcheroo_unregister_client(struct pci_dev *pdev)
 		kfree(client);
 	}
 	if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
-		printk(KERN_INFO "vga_switcheroo: disabled\n");
-		vga_switcheroo_debugfs_fini(&vgasr_priv);
-		vgasr_priv.active = false;
+		vga_switcheroo_disable();
 	}
 	mutex_unlock(&vgasr_mutex);
 }
@@ -262,12 +309,13 @@ static int vga_switcheroo_show(struct seq_file *m, void *v)
 	int i = 0;
 	mutex_lock(&vgasr_mutex);
 	list_for_each_entry(client, &vgasr_priv.clients, list) {
-		seq_printf(m, "%d:%s%s:%c:%s%s:%s\n", i,
+		seq_printf(m, "%d:%s%s:%c:%s%s:%s:%s\n", i,
 			   client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" : "IGD",
 			   client_is_vga(client) ? "" : "-Audio",
 			   client->active ? '+' : ' ',
 			   client->driver_power_control ? "Dyn" : "",
 			   client->pwr_state ? "Pwr" : "Off",
+			   client_id(client) == mux_id ? "mux" : "",
 			   pci_name(client->pdev));
 		i++;
 	}
@@ -304,6 +352,15 @@ static int vga_switchoff(struct vga_switcheroo_client *client)
 	return 0;
 }
 
+static int vga_switch_mux_to(int client_id)
+{
+	int ret = vgasr_priv.handler->switchto(client_id);
+	if (ret == 0) {
+		mux_id = client_id;
+	}
+	return ret;
+}
+
 static void set_audio_state(int id, int state)
 {
 	struct vga_switcheroo_client *client;
@@ -353,7 +410,7 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
 		console_unlock();
 	}
 
-	ret = vgasr_priv.handler->switchto(new_client->id);
+	ret = vga_switch_mux_to(new_client->id);
 	if (ret)
 		return ret;
 
@@ -468,7 +525,7 @@ vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf,
 	vgasr_priv.delayed_switch_active = false;
 
 	if (just_mux) {
-		ret = vgasr_priv.handler->switchto(client_id);
+		ret = vga_switch_mux_to(client_id);
 		goto out;
 	}