[Intel-gfx] [RFC 09/10] drm/i915: Trivial virtual engine implementation

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-01-25 13:33:32)
> -       if (engine && ((caps & engine->caps) != caps))
> -               return -EINVAL;
> +               do {
> +                       engine = i915->engine[_VCS(instance)];
> +                       instance ^= 1;
> +                       vcs_instances--;
> +               } while ((caps & engine->caps) != caps && vcs_instances > 0);
> +
> +               if ((caps & engine->caps) != caps)
> +                       return -EINVAL;
> +
> +               timeline = i915_gem_context_lookup_timeline_class(eb->ctx,
> +                                                                 VIDEO_DECODE_CLASS);
> +               spin_lock_irq(&timeline->lock);
> +               prev_req = list_first_entry_or_null(&timeline->requests,
> +                                                   struct drm_i915_gem_request,
> +                                                   ctx_link);
> +               spin_unlock_irq(&timeline->lock);

This isn't doing anything yet as we aren't using the timeline. The idea
is sound though, we need to rejig timelines to make them more flexible
so that we can combine them to use one per-queue. Ok.
-Chris