[PATCH v2 3/7] vga_switcheroo: Add pre_switch callback to client ops

[Thomas Zimmermann <tzimmermann@suse.de>]

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>
---
 drivers/gpu/vga/vga_switcheroo.c |  4 +++-
 include/linux/vga_switcheroo.h   | 11 ++++++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 22cf52b78b75..bdf1e56ae891 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -733,8 +733,10 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
 	if (!active->driver_power_control)
 		set_audio_state(active->id, VGA_SWITCHEROO_OFF);
 
+	if (new_client->ops->pre_switch)
+		new_client->ops->pre_switch(new_client->pdev);
 #if defined(CONFIG_FB)
-	if (new_client->fb_info)
+	else if (new_client->fb_info)
 		fb_switch_outputs(new_client->fb_info);
 #endif
 
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);
 };
 
-- 
2.54.0