[PATCH v2 2/2] drm/virtio: Add hotplug_mode_update property to ensure position info is read (v2)

[Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>]

Some compositors (mainly Mutter) needs this property to be set in order
to read suggested_x/y values. This property, along with suggested_x/y
will be useful for virtual GPU drivers to share the Host output/window
layout with the Guest compositor.

v2: Improve the commit message.

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 af6ffb696086..8689a589d3d2 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -260,6 +260,8 @@ 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