Using drm_exec for TTMs BO eviction

[Christian König]

Hi guys,

We recently ran into a problem with deadlocks during eviction and while back Thomas worked on a patch set which was going into the direction of solving this.

So I simplified it to just the functionality needed to resolve this issue at. The resulting patch set is just the initial first step of using drm_exec in TTM for locking BOs during eviction.

Should a deadlock happen the drm_exec object is now used to resolve it and prelock the contended object. This approach solves this the ENOMEM issue on contending evictions quite nicely.

Please review and comment,
Christian.