drm_dev_ref — Take reference of a DRM device
| void drm_dev_ref ( | struct drm_device * dev ); | 
   This increases the ref-count of dev by one. You *must* already own a
   reference when calling this. Use drm_dev_unref to drop this reference
   again.
   
This function never fails. However, this function does not provide *any* guarantee whether the device is alive or running. It only provides a reference to the object and the memory associated with it.