[Intel-gfx] [PATCH 5/7] drm/i915: avoid emiting semaphore wait on GEN8 when seqno wrap happened.

[Daniel Vetter]

On Mon, Aug 04, 2014 at 11:15:17AM -0700, Rodrigo Vivi wrote:

This commit message is too thin.

> C: Ben Widawsky <ben at bwidawsk.net>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

Does this blow up with Mika's seqno wrap testcase? If so please add the
right Testcase: line, if not, how can we repro this?
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 30 +++++++++++++++++++++---------
>  1 file changed, 21 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 2e566e0..cd30b39 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -867,15 +867,26 @@ gen8_ring_sync(struct intel_engine_cs *waiter,
>  	if (ret)
>  		return ret;
>  
> -	intel_ring_emit(waiter, MI_SEMAPHORE_WAIT |
> -				MI_SEMAPHORE_GLOBAL_GTT |
> -				MI_SEMAPHORE_POLL |
> -				MI_SEMAPHORE_SAD_GTE_SDD);
> -	intel_ring_emit(waiter, seqno);
> -	intel_ring_emit(waiter,
> -			lower_32_bits(GEN8_WAIT_OFFSET(waiter, signaller->id)));
> -	intel_ring_emit(waiter,
> -			upper_32_bits(GEN8_WAIT_OFFSET(waiter, signaller->id)));
> +	/* If seqno wrap happened, omit the wait with no-ops */
> +	if (likely(!i915_gem_has_seqno_wrapped(waiter->dev, seqno))) {
> +		intel_ring_emit(waiter, MI_SEMAPHORE_WAIT |
> +					MI_SEMAPHORE_GLOBAL_GTT |
> +					MI_SEMAPHORE_POLL |
> +					MI_SEMAPHORE_SAD_GTE_SDD);
> +		intel_ring_emit(waiter, seqno);
> +		intel_ring_emit(waiter,
> +				lower_32_bits(GEN8_WAIT_OFFSET(waiter,
> +							       signaller->id)));
> +		intel_ring_emit(waiter,
> +				upper_32_bits(GEN8_WAIT_OFFSET(waiter,
> +							       signaller->id)));
> +	} else {
> +		intel_ring_emit(waiter, MI_NOOP);
> +		intel_ring_emit(waiter, MI_NOOP);
> +		intel_ring_emit(waiter, MI_NOOP);
> +		intel_ring_emit(waiter, MI_NOOP);
> +	}
> +
>  	intel_ring_advance(waiter);
>  	return 0;
>  }
> @@ -2572,6 +2583,7 @@ int intel_init_vebox_ring_buffer(struct drm_device *dev)
>  			ring->semaphore.mbox.signal[BCS] = GEN6_BVESYNC;
>  			ring->semaphore.mbox.signal[VECS] = GEN6_NOSYNC;
>  			ring->semaphore.mbox.signal[VCS2] = GEN6_NOSYNC;
> +
>  		}
>  	}
>  	ring->init = init_ring_common;
> -- 
> 1.9.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch