drm/amdgpu: simplify eviction fence suspend/resume

The basic idea in this redesign is to add an eviction fence only in UQ resume path. When userqueue is not present, keep ev_fence as NULL

Main changes are:

• do not create the eviction fence during evf_mgr_init, keeping evf_mgr->ev_fence=NULL until UQ get active.
• do not replace the ev_fence in evf_resume path, but replace it only in uq_resume path, so remove all the unnecessary code from ev_fence_resume.
• add a new helper function (amdgpu_userqueue_ensure_ev_fence) which will do the following:
  • flush any pending uq_resume work, so that it could create an eviction_fence
  • if there is no pending uq_resume_work, add a uq_resume work and wait for it to execute so that we always have a valid ev_fence
• call this helper function from two places, to ensure we have a valid ev_fence:
  • when a new uq is created
  • when a new uq completion fence is created

v2: Worked on review comments by Christian. v3: Addressed few more review comments by Christian. v4: Move mutex lock outside of the amdgpu_userqueue_suspend() function (Christian).

Cc: Alex Deucher alexander.deucher@amd.com Reviewed-by: Christian König christian.koenig@amd.com Signed-off-by: Arvind Yadav arvind.yadav@amd.com Signed-off-by: Shashank Sharma shashank.sharma@amd.com

Testing is done on Navi33

Adding testing results :

• Able to launch Desktop.
• Glxgear is running successfully
• unigen_heaven is running successfully.