[PATCH 3/6] vga-switcheroo: notify clients of pending/completed switch events

[Daniel Dadap]

Add a new vga-switcheroo client callback to allow clients to register
for receiving notifications when a mux switch is pending, completed,
or failed. This allows individual client drivers to prepare for or
respond to mux switches to and from the registered client device.

Signed-off-by: Daniel Dadap <ddadap at nvidia.com>
---
 drivers/gpu/vga/vga_switcheroo.c | 29 ++++++++++++++++++++++++++++-
 include/linux/vga_switcheroo.h   | 18 ++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index a4fc78c4bf4f..6392dc92696b 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -756,14 +756,41 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client,
 	if (new_client->fb_info)
 		fbcon_remap_all(new_client->fb_info);
 
+	if (active->ops->notify)
+		active->ops->notify(active->pdev,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_AWAY,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_PENDING);
+	if (new_client->ops->notify)
+		new_client->ops->notify(new_client->pdev,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_TO,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_PENDING);
+
 	active->switched = false;
 	mutex_lock(&vgasr_priv.mux_hw_lock);
 	ret = vgasr_priv.handler->switchto(new_client->id);
 	mutex_unlock(&vgasr_priv.mux_hw_lock);
-	if (ret)
+	if (ret) {
+		if (active->ops->notify)
+			active->ops->notify(active->pdev,
+				VGA_SWITCHEROO_NOTIFY_SWITCH_AWAY,
+				VGA_SWITCHEROO_NOTIFY_SWITCH_FAILED);
+		if (new_client->ops->notify)
+			new_client->ops->notify(new_client->pdev,
+				VGA_SWITCHEROO_NOTIFY_SWITCH_TO,
+				VGA_SWITCHEROO_NOTIFY_SWITCH_FAILED);
 		return ret;
+	}
 	new_client->switched = true;
 
+	if (active->ops->notify)
+		active->ops->notify(active->pdev,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_AWAY,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_COMPLETE);
+	if (new_client->ops->notify)
+		new_client->ops->notify(new_client->pdev,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_TO,
+			VGA_SWITCHEROO_NOTIFY_SWITCH_COMPLETE);
+
 	if (new_client->ops->reprobe)
 		new_client->ops->reprobe(new_client->pdev);
 
diff --git a/include/linux/vga_switcheroo.h b/include/linux/vga_switcheroo.h
index 63e6d6e5786e..2dc8ebc84fd4 100644
--- a/include/linux/vga_switcheroo.h
+++ b/include/linux/vga_switcheroo.h
@@ -90,6 +90,17 @@ enum vga_switcheroo_client_id {
 	VGA_SWITCHEROO_MAX_CLIENTS,
 };
 
+enum vga_switcheroo_notify_direction {
+	VGA_SWITCHEROO_NOTIFY_SWITCH_TO,
+	VGA_SWITCHEROO_NOTIFY_SWITCH_AWAY,
+};
+
+enum vga_switcheroo_notify_action {
+	VGA_SWITCHEROO_NOTIFY_SWITCH_PENDING,
+	VGA_SWITCHEROO_NOTIFY_SWITCH_COMPLETE,
+	VGA_SWITCHEROO_NOTIFY_SWITCH_FAILED,
+};
+
 /**
  * struct vga_switcheroo_handler - handler callbacks
  * @init: initialize handler.
@@ -134,6 +145,10 @@ struct vga_switcheroo_handler {
  * 	Mandatory. The client should return false if a user space process
  * 	has one of its device files open
  * @gpu_bound: notify the client id to audio client when the GPU is bound.
+ * @notify: notify clients of pending and completed switches
+ *	Optional. This gets called for both active and inactive clients,
+ *	before a switch begins, and after a switch successfully completes
+ *	or fails.
  *
  * Client callbacks. A client can be either a GPU or an audio device on a GPU.
  * The @set_gpu_state and @can_switch methods are mandatory, @reprobe may be
@@ -145,6 +160,9 @@ struct vga_switcheroo_client_ops {
 	void (*reprobe)(struct pci_dev *dev);
 	bool (*can_switch)(struct pci_dev *dev);
 	void (*gpu_bound)(struct pci_dev *dev, enum vga_switcheroo_client_id);
+	void (*notify)(struct pci_dev *dev,
+		       enum vga_switcheroo_notify_direction,
+		       enum vga_switcheroo_notify_action);
 };
 
 #if defined(CONFIG_VGA_SWITCHEROO)
-- 
2.18.4