Hi,
I've been debugging omapdrm issues on top of the latest drm mainline changes. Sometimes a drm_framebuffer ref count drops to -1 when aborting a drm application, or unloading the modules.
The setup is very basic, just a single crtc with the crtc's primary plane.
What seems to happen is:
- App is started
- fb is created, and taken into use by omapdrm. omapdrm takes a ref to the fb.
- the app is starts to shut down
- drm_framebuffer_remove is called
- fb->refcount.refcount > 1, so it goes to disable stuff
- drm_plane_force_disable is called for the primary plane
- drm_plane_force_disable does plane->disable_plane, which on omapdrm puts stuff on a workqueue as plane cannot be disabled immediately
- drm_plane_force_disable calls __drm_framebuffer_unreference()
- at the end of drm_framebuffer_remove(), there's drm_framebuffer_unreference, which causes ref count to go to zero, and the fb to be destroyed
- a bit later, the queued work is ran, which does drm_framebuffer_unreference(), and ref count goes to -1. Here omapdrm is removing the ref that had been taken in the beginning.
So the explicit unref done by drm_plane_force_disable() seems a bit out of place. I can't figure out which drm_framebuffer_reference() would be the matching one for the unref done by drm_plane_force_disable().
Any ideas what ref is that? Or is the __drm_framebuffer_unreference() extra in drm_plane_force_disable()?
Tomi