Re: [igt-dev] [PATCH i-g-t v2 5/5] test/prime_vgem: use the gem_engine_topology library

[Andi Shyti <andi.shyti@intel.com>]

Hi Ram,

> > > > > just a nitpick
> > > > > 
> > > > > > -	execbuf.flags = ring | flags;
> > > > > > +	execbuf.flags = e ? e->flags : I915_EXEC_DEFAULT;
> > > > > 
> > > > > Because we are moving to the new engine naming, the
> > > > > "I915_EXEC_DEFAULT" engine, conceptually, should not be used.
> > > > > 
> > > > > Politically, with Tvrtko, we agreed that he default engine now
> > > > > is "I915_ENGINE_CLASS_RENDER", it's not the best as solution, but
> > > > > works.
> > > > 
> > > > I totally don't remember I ever suggested to use class or even it was
> > > > discussed.  :) Didn't we say to just use zero?
> > > Can't use I915_EXEC_RENDER instead of DEFAULT!? because that will be
> > > exec_flag for render class right?
> > 
> > No, I915_EXEC_RENDER is 1 so if the context has engine map configured that
> > will map to 2nd engine in the map - which is not rcs0.
> > 
> > We are relying here on rcs0 being first (index 0). But that is also not
> > reliable. We need a lookup helper to be more robust going forward.
> something like below?
> 
> get_engine_exec_flag_for_class(fd, e, class) __for_each_physical_engine(fd, e) \
>                                                 if (e->class == class) { \
>                                                         e->flags;
>                                                         break; \
>                                                 } \
>                                                 0;

I guess we would need to query the gpu, fetch the engine list and
search the needed engine, somthing similar to
gem_context_lookup_engine() in gem_engine_topology.c

if you want you can give it a shot, otherwise I can do it over
the weekend and send it on Monday.

Andi
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