On 2019.06.21 20:13:13 +0100, Chris Wilson wrote:
> Preempt-to-busy uses a GPU semaphore to enforce an idle-barrier across
> preemption, but mediated gvt does not fully support semaphores.
>

Current looks semaphore is still used from emit_fini_breadcrumb which
caused gvt error, gvt may support memory based semaphore but not for
reg based.

> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/gt/intel_lrc.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index c8a0c9b32764..d8649e759ce8 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -294,6 +294,9 @@ static inline bool need_preempt(const struct intel_engine_cs *engine,
>  {
>  	int last_prio;
>  
> +	if (!intel_engine_has_preemption(engine))
> +		return false;
> +
>  	/*
>  	 * Check if the current priority hint merits a preemption attempt.
>  	 *
> @@ -890,6 +893,9 @@ need_timeslice(struct intel_engine_cs *engine, const struct i915_request *rq)
>  {
>  	int hint;
>  
> +	if (!intel_engine_has_preemption(engine))
> +		return false;
> +
>  	if (list_is_last(&rq->sched.link, &engine->active.requests))
>  		return false;
>  
> @@ -2672,10 +2678,11 @@ void intel_execlists_set_default_submission(struct intel_engine_cs *engine)
>  	engine->unpark = NULL;
>  
>  	engine->flags |= I915_ENGINE_SUPPORTS_STATS;
> -	if (!intel_vgpu_active(engine->i915))
> +	if (!intel_vgpu_active(engine->i915)) {
>  		engine->flags |= I915_ENGINE_HAS_SEMAPHORES;
> -	if (HAS_LOGICAL_RING_PREEMPTION(engine->i915))
> -		engine->flags |= I915_ENGINE_HAS_PREEMPTION;
> +		if (HAS_LOGICAL_RING_PREEMPTION(engine->i915))
> +			engine->flags |= I915_ENGINE_HAS_PREEMPTION;
> +	}
>  }
>  
>  static void execlists_destroy(struct intel_engine_cs *engine)
> -- 
> 2.20.1
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
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