[PATCH RFC v2] vga_switcheroo: restore mux and power states upon resume from hibernation.

[Stefan Demharter <stefan.demharter@gmx.net>]

Saves the current state of the mux and restores it upon resume from hibernation.
This is needed for muxed systems because the state of the mux doesn't survive a
hibernation-resume cycle. Furthermore also restores the power state of a GPU
to OFF after resume from hibernation if it was OFF before hibernation.

Signed-off-by: Stefan Demharter <stefan.demharter@gmx.net>
---
 drivers/gpu/vga/vga_switcheroo.c | 96 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 85 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index ec0ae2d..85f41b9 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 +73,64 @@ static struct vgasr_priv vgasr_priv = {
 	.clients = LIST_HEAD_INIT(vgasr_priv.clients),
 };
 
+#define MUX_STATE_UNDEFINED (-1)
+/*
+ * The next variable stores the state of the mux
+ * so it can be restored upon resume from hibernation.
+ */
+static int mux_state = MUX_STATE_UNDEFINED;
+
+static void vga_restore_mux(void)
+{
+	if (mux_state != MUX_STATE_UNDEFINED) {
+		int ret;
+		pr_info("vga_switcheroo: restoring mux state to %s\n",
+			mux_state == VGA_SWITCHEROO_IGD ? "IGD" : "DIS");
+
+		ret = vgasr_priv.handler->switchto(mux_state);
+		if (ret)
+			pr_warn("vga_switcheroo: mux switch failed (%d)\n", ret);
+	}
+}
+
+static void vga_restore_power_state(void)
+{
+	struct vga_switcheroo_client *client;
+
+	if (!vgasr_priv.handler->power_state)
+		return;
+
+	list_for_each_entry(client, &vgasr_priv.clients, list) {
+		if (client_is_vga(client) && client->pwr_state == VGA_SWITCHEROO_OFF) {
+			pr_info("vga_switcheroo: setting power state of %s to OFF\n",
+				client->id == VGA_SWITCHEROO_IGD ? "IGD" : "DIS");
+			vgasr_priv.handler->power_state(client->id, client->pwr_state);
+		}
+	}
+}
+
+/*
+ * Handle resume from hibernation:
+ * Restore mux state and power states for switcheroo controlled GPUs.
+ */
+static int vga_resume(struct notifier_block *nb, unsigned long action, void *unused)
+{
+	switch (action) {
+	case PM_POST_HIBERNATION:
+		mutex_lock(&vgasr_mutex);
+		vga_restore_mux();
+		vga_restore_power_state();
+		mutex_unlock(&vgasr_mutex);
+		break;
+	}
+	return 0;
+}
+
+static struct notifier_block vga_switcheroo_pm_nb = {
+	.notifier_call = vga_resume,
+	.priority = 0,
+};
+
 static bool vga_switcheroo_ready(void)
 {
 	/* we're ready if we get two clients + handler */
@@ -84,6 +143,8 @@ static void vga_switcheroo_enable(void)
 	int ret;
 	struct vga_switcheroo_client *client;
 
+	pr_info("vga_switcheroo: enabled\n");
+
 	/* call the handler to init */
 	if (vgasr_priv.handler->init)
 		vgasr_priv.handler->init();
@@ -99,6 +160,15 @@ static void vga_switcheroo_enable(void)
 	}
 	vga_switcheroo_debugfs_init(&vgasr_priv);
 	vgasr_priv.active = true;
+	register_pm_notifier(&vga_switcheroo_pm_nb);
+}
+
+void vga_switcheroo_disable(void)
+{
+	unregister_pm_notifier(&vga_switcheroo_pm_nb);
+	vgasr_priv.active = false;
+	vga_switcheroo_debugfs_fini(&vgasr_priv);
+	pr_info("vga_switcheroo: disabled\n");
 }
 
 int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
@@ -111,7 +181,6 @@ int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
 
 	vgasr_priv.handler = handler;
 	if (vga_switcheroo_ready()) {
-		printk(KERN_INFO "vga_switcheroo: enabled\n");
 		vga_switcheroo_enable();
 	}
 	mutex_unlock(&vgasr_mutex);
@@ -124,9 +193,7 @@ 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);
 }
@@ -155,7 +222,6 @@ static int register_client(struct pci_dev *pdev,
 		vgasr_priv.registered_clients++;
 
 	if (vga_switcheroo_ready()) {
-		printk(KERN_INFO "vga_switcheroo: enabled\n");
 		vga_switcheroo_enable();
 	}
 	mutex_unlock(&vgasr_mutex);
@@ -235,9 +301,7 @@ 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);
 }
@@ -262,10 +326,11 @@ 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_id(client) == mux_state ? "mux" : "",
 			   client->driver_power_control ? "Dyn" : "",
 			   client->pwr_state ? "Pwr" : "Off",
 			   pci_name(client->pdev));
@@ -304,6 +369,15 @@ static int vga_switchoff(struct vga_switcheroo_client *client)
 	return 0;
 }
 
+static int vga_switchto(int client_id)
+{
+	int ret = vgasr_priv.handler->switchto(client_id);
+
+	if (ret == 0)
+		mux_state = client_id;
+	return ret;
+}
+
 static void set_audio_state(int id, int state)
 {
 	struct vga_switcheroo_client *client;
@@ -353,7 +427,7 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
 		console_unlock();
 	}
 
-	ret = vgasr_priv.handler->switchto(new_client->id);
+	ret = vga_switchto(new_client->id);
 	if (ret)
 		return ret;
 
@@ -468,7 +542,7 @@ 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_switchto(client_id);
 		goto out;
 	}
 
-- 
1.8.5.3