vga_switcheroo: Add pre_switch callback to client ops

Add pre_switch to struct vga_switcheroo_client_ops to inform the
switcheroo client about upcoming switches of the outputs.

This callback is intended to replace the hard-coded call to fbdev's
fb_switch_outputs(). With DRM supporting more clients than just fbdev
emulation, something more flexible is required.

v2:
- remove non-sensical gpu_bound documentation (Sashiko)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Helge Deller <deller@gmx.de>
Link: https://patch.msgid.link/20260709092215.168172-4-tzimmermann@suse.de

1 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/vga_switcheroo.h b/include/linux/vga_switcheroo.h
index 7e6ac0114d55..4422daca9ceb 100644
--- a/include/linux/vga_switcheroo.h
+++ b/include/linux/vga_switcheroo.h
@@ -133,17 +133,22 @@ struct vga_switcheroo_handler {
  * @can_switch: check if the device is in a position to switch now.
  * 	Mandatory. The client should return false if a user space process
  * 	has one of its device files open
+ * @pre_switch: prepare switch
+ *	Optional. This gets called before switching the outputs to the
+ *	GPU. Allows drivers to prepare for the switch.
  * @gpu_bound: notify the client id to audio client when the GPU is bound.
  *
  * 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
- * set to NULL. For audio clients, the @reprobe member is bogus.
- * OTOH, @gpu_bound is only for audio clients, and not used for GPU clients.
+ * The @set_gpu_state and @can_switch methods are mandatory, @pre_switch and
+ * @reprobe may be set to NULL. For audio clients, the @pre_switch and
+ * @reprobe members are bogus. OTOH, @gpu_bound is only for audio clients,
+ * and not used for GPU clients.
  */
 struct vga_switcheroo_client_ops {
 	void (*set_gpu_state)(struct pci_dev *dev, enum vga_switcheroo_state);
 	void (*reprobe)(struct pci_dev *dev);
 	bool (*can_switch)(struct pci_dev *dev);
+	void (*pre_switch)(struct pci_dev *dev);
 	void (*gpu_bound)(struct pci_dev *dev, enum vga_switcheroo_client_id);
 };