Commits
Chris Wilson committed 9d7730914f4
drm/i915: Preallocate next seqno before touching the ring Based on the work by Mika Kuoppala, we realised that we need to handle seqno wraparound prior to committing our changes to the ring. The most obvious point then is to grab the seqno inside intel_ring_begin(), and then to reuse that seqno for all ring operations until the next request. As intel_ring_begin() can fail, the callers must already be prepared to handle such failure and so we can safely add further checks. This patch looks like it should be split up into the interface changes and the tweaks to move seqno wrapping from the execbuffer into the core seqno increment. However, I found no easy way to break it into incremental steps without introducing further broken behaviour. v2: Mika found a silly mistake and a subtle error in the existing code; inside i915_gem_retire_requests() we were resetting the sync_seqno of the target ring based on the seqno from this ring - which are only related by the order of their allocation, not retirement. Hence we were applying the optimisation that the rings were synchronised too early, fortunately the only real casualty there is the handling of seqno wrapping. v3: Do not forget to reset the sync_seqno upon module reinitialisation, ala resume. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=863861 Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> [v2] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>