Re: [PATCH v4 12/15] drm/i915/huc: stall media submission until HuC is loaded

["Ye, Tony" <tony.ye@intel.com>]

On 9/8/2022 5:16 PM, Daniele Ceraolo Spurio wrote:
> Wait on the fence to be signalled to avoid the submissions finding HuC
> not yet loaded.
>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Tony Ye <tony.ye@intel.com>
> Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_huc.h |  6 ++++++
>   drivers/gpu/drm/i915/i915_request.c    | 24 ++++++++++++++++++++++++
>   2 files changed, 30 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_huc.h b/drivers/gpu/drm/i915/gt/uc/intel_huc.h
> index 915d281c1c72..52db03620c60 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_huc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_huc.h
> @@ -81,6 +81,12 @@ static inline bool intel_huc_is_loaded_by_gsc(const struct intel_huc *huc)
>   	return huc->fw.loaded_via_gsc;
>   }
>   
> +static inline bool intel_huc_wait_required(struct intel_huc *huc)
> +{
> +	return intel_huc_is_used(huc) && intel_huc_is_loaded_by_gsc(huc) &&
> +	       !intel_huc_is_authenticated(huc);
> +}
> +
>   void intel_huc_load_status(struct intel_huc *huc, struct drm_printer *p);
>   
>   #endif
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 62fad16a55e8..77f45a3cb01f 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -1621,6 +1621,20 @@ i915_request_await_object(struct i915_request *to,
>   	return ret;
>   }
>   
> +static void i915_request_await_huc(struct i915_request *rq)
> +{
> +	struct intel_huc *huc = &rq->context->engine->gt->uc.huc;
> +
> +	/* don't stall kernel submissions! */
> +	if (!rcu_access_pointer(rq->context->gem_context))
> +		return;
> +
> +	if (intel_huc_wait_required(huc))
> +		i915_sw_fence_await_sw_fence(&rq->submit,
> +					     &huc->delayed_load.fence,
> +					     &rq->submitq);
> +}
> +
>   static struct i915_request *
>   __i915_request_ensure_parallel_ordering(struct i915_request *rq,
>   					struct intel_timeline *timeline)
> @@ -1702,6 +1716,16 @@ __i915_request_add_to_timeline(struct i915_request *rq)
>   	struct intel_timeline *timeline = i915_request_timeline(rq);
>   	struct i915_request *prev;
>   
> +	/*
> +	 * Media workloads may require HuC, so stall them until HuC loading is
> +	 * complete. Note that HuC not being loaded when a user submission
> +	 * arrives can only happen when HuC is loaded via GSC and in that case
> +	 * we still expect the window between us starting to accept submissions
> +	 * and HuC loading completion to be small (a few hundred ms).
> +	 */
> +	if (rq->engine->class == VIDEO_DECODE_CLASS)
> +		i915_request_await_huc(rq);
> +

Acked-by: Tony Ye <tony.ye@intel.com>

Thanks,

Tony

>   	/*
>   	 * Dependency tracking and request ordering along the timeline
>   	 * is special cased so that we can eliminate redundant ordering