drm: Document device unplug infrastructure

While at it, also ocd and give them a consistent drm_dev_ prefix, like
the other device instance functionality. Plus move the functions into
the right places.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170802115604.12734-3-daniel.vetter@ffwll.ch

1 files changed, 21 insertions, 3 deletions

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 2ed2d919beae..39191e5c240e 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -291,7 +291,7 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
 
 	if (!minor) {
 		return ERR_PTR(-ENODEV);
-	} else if (drm_device_is_unplugged(minor->dev)) {
+	} else if (drm_dev_is_unplugged(minor->dev)) {
 		drm_dev_unref(minor->dev);
 		return ERR_PTR(-ENODEV);
 	}
@@ -364,7 +364,22 @@ void drm_put_dev(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_put_dev);
 
-void drm_unplug_dev(struct drm_device *dev)
+static void drm_device_set_unplugged(struct drm_device *dev)
+{
+	smp_wmb();
+	atomic_set(&dev->unplugged, 1);
+}
+
+/**
+ * drm_dev_unplug - unplug a DRM device
+ * @dev: DRM device
+ *
+ * This unplugs a hotpluggable DRM device, which makes it inaccessible to
+ * userspace operations. Entry-points can use drm_dev_is_unplugged(). This
+ * essentially unregisters the device like drm_dev_unregister(), but can be
+ * called while there are still open users of @dev.
+ */
+void drm_dev_unplug(struct drm_device *dev)
 {
 	/* for a USB device */
 	if (drm_core_check_feature(dev, DRIVER_MODESET))
@@ -383,7 +398,7 @@ void drm_unplug_dev(struct drm_device *dev)
 	}
 	mutex_unlock(&drm_global_mutex);
 }
-EXPORT_SYMBOL(drm_unplug_dev);
+EXPORT_SYMBOL(drm_dev_unplug);
 
 /*
  * DRM internal mount
@@ -835,6 +850,9 @@ EXPORT_SYMBOL(drm_dev_register);
  * drm_dev_register() but does not deallocate the device. The caller must call
  * drm_dev_unref() to drop their final reference.
  *
+ * A special form of unregistering for hotpluggable devices is drm_dev_unplug(),
+ * which can be called while there are still open users of @dev.
+ *
  * This should be called first in the device teardown code to make sure
  * userspace can't access the device instance any more.
  */