[PATCH v1 2/2] drm/virtio: Add the hotplug_mode_update property for rescanning of modes

[Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>]

Setting this property will allow the userspace to look for new modes or
position info when a hotplug event occurs. This is really helpful for
virtual GPU drivers to handle Host window resizing events which are
propogated as hotplug interrupts to the Guest drivers. Mutter already
uses this property while configuring the outputs.

Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Dongwon Kim <dongwon.kim@xxxxxxxxx>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
---
 drivers/gpu/drm/virtio/virtgpu_display.c | 14 ++++++++++++++
 drivers/gpu/drm/virtio/virtgpu_drv.h     |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
index 868b0183c6df..09a8089bb62a 100644
--- a/drivers/gpu/drm/virtio/virtgpu_display.c
+++ b/drivers/gpu/drm/virtio/virtgpu_display.c
@@ -286,6 +286,8 @@ static int vgdev_output_init(struct virtio_gpu_device *vgdev, int index)
 				   dev->mode_config.suggested_x_property, 0);
 	drm_object_attach_property(&connector->base,
 				   dev->mode_config.suggested_y_property, 0);
+	drm_object_attach_property(&connector->base,
+				   vgdev->hotplug_mode_update_property, 1);
 
 	drm_simple_encoder_init(dev, encoder, DRM_MODE_ENCODER_VIRTUAL);
 	drm_encoder_helper_add(encoder, &virtio_gpu_enc_helper_funcs);
@@ -336,6 +338,17 @@ static const struct drm_mode_config_funcs virtio_gpu_mode_funcs = {
 	.atomic_commit = drm_atomic_helper_commit,
 };
 
+static void
+virtio_gpu_create_hotplug_mode_update_property(struct virtio_gpu_device *vgdev)
+{
+	if (vgdev->hotplug_mode_update_property)
+		return;
+
+	vgdev->hotplug_mode_update_property =
+		drm_property_create_range(vgdev->ddev, DRM_MODE_PROP_IMMUTABLE,
+					  "hotplug_mode_update", 0, 1);
+}
+
 int virtio_gpu_modeset_init(struct virtio_gpu_device *vgdev)
 {
 	int i, ret;
@@ -355,6 +368,7 @@ int virtio_gpu_modeset_init(struct virtio_gpu_device *vgdev)
 
 	vgdev->ddev->mode_config.fb_modifiers_not_supported = true;
 	drm_mode_create_suggested_offset_properties(vgdev->ddev);
+	virtio_gpu_create_hotplug_mode_update_property(vgdev);
 
 	for (i = 0 ; i < vgdev->num_scanouts; ++i)
 		vgdev_output_init(vgdev, i);
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index b7a64c7dcc2c..35f940302e24 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -257,6 +257,8 @@ struct virtio_gpu_device {
 	uint64_t capset_id_mask;
 	struct list_head cap_cache;
 
+	struct drm_property *hotplug_mode_update_property;
+
 	/* protects uuid state when exporting */
 	spinlock_t resource_export_lock;
 	/* protects map state and host_visible_mm */
-- 
2.37.2