[Intel-gfx] [PATCH 1/5] drm/i915: Only enqueue already completed requests

[Chris Wilson]

Quoting Mika Kuoppala (2019-08-06 15:25:49)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > If we are asked to submit a completed request, just move it onto the
> > active-list without modifying it's payload.
> >
> 
> If the seqno is there then there is no need to write
> it yes.
> 
> But I am not at all certain that I deduced the 'why'
> part correctly so please spell it out.

Because if the request is complete, we may have moved the ring->head
during retirement (or in the new reset-on-completion) past the breadcrumb
and generate warnings for appearing to go backwards.
-Chris