[Intel-gfx] [PATCH 8/8] drm/i915: Keep track of reserved execlist ports

[Chris Wilson]

Quoting Mika Kuoppala (2017-09-12 09:36:18)
>  static void execlists_dequeue(struct intel_engine_cs *engine)
>  {
> -       struct drm_i915_gem_request *last;
>         struct intel_engine_execlist * const el = &engine->execlist;
> -       struct execlist_port *port = execlist_port_head(el);
> -       const struct execlist_port * const last_port = execlist_port_tail(el);
> +       struct execlist_port *port;
> +       struct drm_i915_gem_request *last;
>         struct rb_node *rb;
>         bool submit = false;
>  
> -       last = port_request(port);
> -       if (last)
> +       if (execlist_active_ports(el)) {
> +               port = execlist_port_tail(el);
> +               last = port_request(port);
> +
>                 /* WaIdleLiteRestore:bdw,skl
>                  * Apply the wa NOOPs to prevent ring:HEAD == req:TAIL
>                  * as we resubmit the request. See gen8_emit_breadcrumb()
> @@ -414,6 +419,10 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
>                  * request.
>                  */
>                 last->tail = last->wa_tail;
> +       } else {
> +               port = NULL;
> +               last = NULL;
> +       }
>  
>         /* Hardware submission is through 2 ports. Conceptually each port
>          * has a (RING_START, RING_HEAD, RING_TAIL) tuple. RING_START is
> @@ -443,6 +452,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
>                 struct i915_priolist *p = rb_entry(rb, typeof(*p), node);
>                 struct drm_i915_gem_request *rq, *rn;
>  
> +               if (!port)
> +                       port = execlist_request_port(el);
> +
>                 list_for_each_entry_safe(rq, rn, &p->requests, priotree.link) {
>                         /*
>                          * Can we combine this request with the current port?
> @@ -461,7 +473,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
>                                  * combine this request with the last, then we
>                                  * are done.
>                                  */

The comment above is now confused, so
/*
 * If we are on the last port and cannot combine
 * this request with the previous, then we are
 * done.
 */
-Chris