Re: [PATCH 5/7] drm/i915: Expose RPCS (SSEU) configuration to userspace (Gen11 only)

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 14/12/2018 13:33, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-12-14 12:34:47)
>> +static int get_sseu(struct i915_gem_context *ctx,
>> +                   struct drm_i915_gem_context_param *args)
>> +{
>> +       struct drm_i915_gem_context_param_sseu user_sseu;
>> +       struct intel_engine_cs *engine;
>> +       struct intel_context *ce;
>> +       int ret;
>> +
>> +       if (args->size == 0)
>> +               goto out;
>> +       else if (args->size < sizeof(user_sseu))
>> +               return -EINVAL;
>> +
>> +       if (copy_from_user(&user_sseu, u64_to_user_ptr(args->value),
>> +                          sizeof(user_sseu)))
>> +               return -EFAULT;
>> +
>> +       if (user_sseu.rsvd1 || user_sseu.rsvd2)
>> +               return -EINVAL;
> 
> I'd vote for s/rsvd2/flags/ straight away as already I can suggest we
> allow for USE_CTX_ENGINE to swap class/instance for engine-id so that we
> can set rpcs for, and not least, a virtual engine.

Hm.. would it be useful? It would just be a way of indirection.

engines = [vcs:0, vcs:1]
ctx.set_map(engines)

And then a):

foreach engine in engines:
	ctx.set_sseu(engine, flags=0)

vs b):

for i = 0; i < len(engines); i++:
	ctx.set_sseu(i, flags=USE_CTX_ENGINE)

So I don't see any benefit. But maybe I missed your idea.

Regards,

Tvrtko

> 
>> +
>> +       engine = intel_engine_lookup_user(ctx->i915,
>> +                                         user_sseu.class,
>> +                                         user_sseu.instance);
>> +       if (!engine)
>> +               return -EINVAL;
> -Chris
> 
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