https://bugs.freedesktop.org/show_bug.cgi?id=108014
--- Comment #9 from Harry Wentland harry.wentland@amd.com ---
All of that being said, that means this is a lot more severe then I thought! :), phew.
Do you mean less severe?
Now onto the actual patch that you sent: what exactly is this supposed to be doing? Are we dereferencing an mstb's port too early somewhere in the DRM MST core?
Imagine this daisy-chain configuration:
GPU > MST display 1 > MST display 2
When unplugging MST display 2 we fail to deallocate the payload allocation for the link between the two MST displays. It looks like the MST connector destroy code tries to do so but fails to do so because it can no longer get a validate_port_ref for the 2nd MST display's port.
Jerry's done a ton of debugging here and give more info. My thoughts are that it seems like Dave designed the drm_dp_mst_* code to deal with it quite well but it got broken at some point, maybe with the introduction of the validated_port_ref, or something else. But even then, all the new changes are good. I've been trying to think how this could be solved but haven't found a solution I'm happy with yet.