[Intel-gfx] [PATCH] drm/i915/guc: Tidy ELSP port assignment

[Chris Wilson]

Quoting Chris Wilson (2017-11-24 12:29:16)
> Since we know that the port is empty, we do not need to extract the
> count from the old request it and copy it over to the new request, or
> attempt to unref the NULL old request pointer.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Cc: Michał Winiarski <michal.winiarski at intel.com>

Oooh, Mika noticed that we no longer skip port[0] if set, as that is no
behind the if (preempt). Oops. As I recall, the intention is that we
only use a maximum of two ports per engine to avoid overflow. If we let
ourselves coalesce onto port[0], we lose track of how many wq are in
flight.

Patch incoming.
-Chris