Re: [PATCH 8/8] drm/i915: Expose RPCS (SSEU) configuration to userspace

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

On 14/08/2018 16:22, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-08-14 15:40:58)
>> +static int
>> +i915_gem_context_reconfigure_sseu(struct i915_gem_context *ctx,
>> +                                 struct intel_engine_cs *engine,
>> +                                 struct intel_sseu sseu)
>> +{
>> +       struct drm_i915_private *i915 = ctx->i915;
>> +       struct i915_request *rq;
>> +       struct intel_ring *ring;
>> +       int ret;
>> +
>> +       lockdep_assert_held(&i915->drm.struct_mutex);
>> +
>> +       /* Submitting requests etc needs the hw awake. */
>> +       intel_runtime_pm_get(i915);
>> +
>> +       i915_retire_requests(i915);
>> +
>> +       /* Now use the RCS to actually reconfigure. */
>> +       engine = i915->engine[RCS];
>> +
>> +       rq = i915_request_alloc(engine, i915->kernel_context);
>> +       if (IS_ERR(rq)) {
>> +               ret = PTR_ERR(rq);
>> +               goto out_put;
>> +       }
>> +
>> +       ret = engine->emit_rpcs_config(rq, ctx, sseu);
>> +       if (ret)
>> +               goto out_add;
>> +
>> +       /* Queue this switch after all other activity */
>> +       list_for_each_entry(ring, &i915->gt.active_rings, active_link) {
>> +               struct i915_request *prev;
>> +
>> +               prev = last_request_on_engine(ring->timeline, engine);
>> +               if (prev)
>> +                       i915_sw_fence_await_sw_fence_gfp(&rq->submit,
>> +                                                        &prev->submit,
>> +                                                        I915_FENCE_GFP);
>> +       }
>> +
>> +       i915_gem_set_global_barrier(i915, rq);
>> +
>> +out_add:
>> +       i915_request_add(rq);
>> +out_put:
>> +       intel_runtime_pm_put(i915);
>> +
>> +       return ret;
> 
> Looks like we should be able to hook this up to a selftest to confirm
> the modification does land in the target context image, and a SRM to
> confirm it loaded.

Lionel wrote an IGT which reads it back via SRM so that should be 
covered. I will be posting the IGT counterpart at some point as well, 
ideally when the agreement on the i915 side is there.

Regards,

Tvrtko
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