[Intel-gfx] [PATCH v5 2/9] drm/i915: Define an engine class enum for the uABI

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-11-09 09:27:33)
> 
> On 09/11/2017 09:13, Lionel Landwerlin wrote:
> > On 08/11/17 19:14, Chris Wilson wrote:
> >> +/*
> >> + * Different engines serve different roles, and there may be more 
> >> than one
> >> + * engine serving each role. enum drm_i915_gem_engine_class provides a
> >> + * classification of the role of the engine, which may be used when 
> >> requesting
> >> + * operations to be performed on a certain subset of engines, or for 
> >> providing
> >> + * information about that group.
> >> + */
> >> +enum drm_i915_gem_engine_class {
> >> +    I915_ENGINE_CLASS_OTHER = 0,
> >> +    I915_ENGINE_CLASS_RENDER = 1,
> >> +    I915_ENGINE_CLASS_COPY = 2,
> >> +    I915_ENGINE_CLASS_VIDEO = 3,
> >> +    I915_ENGINE_CLASS_VIDEO_ENHANCE = 4,
> >> +};
> >> +
> > I've tried to build a bit UI in GPUTop to show this.
> > I'm a bit skeptical about the OTHER type because if this enum is meant 
> > to be extended, then why do we need an OTHER class? We should create new 
> > classes instead.
> 
> Good point, I agree that I cannot find a reason why we would have it in 
> the uAPI. I suspect I was just doing a copy-paste-transform of the 
> hardware definitions from i915_reg.h.

Do we want to keep 0 as undefined? It can be both a nuisance and a
blessing...
-Chris