Re: [PATCH 05/10] drm/i915: Implement MI decode for gen8

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Jun 30, 2014 at 09:53:39AM -0700, Rodrigo Vivi wrote:
> Ipehr just carries Dword 0 and on Gen 8, offsets are located
> on Dword 2 and 3 of MI_SEMAPHORE_WAIT.
> 
> This implementation was based on Ben's work and on Ville's suggestion for Ben
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Ben Widawsky <ben@bwidawsk.net>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 42 ++++++++++++++++++++++-------------------
>  1 file changed, 23 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 0217a41..66e2481 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2784,12 +2784,7 @@ static bool
>  ipehr_is_semaphore_wait(struct drm_device *dev, u32 ipehr)
>  {
>  	if (INTEL_INFO(dev)->gen >= 8) {
> -		/*
> -		 * FIXME: gen8 semaphore support - currently we don't emit
> -		 * semaphores on bdw anyway, but this needs to be addressed when
> -		 * we merge that code.
> -		 */
> -		return false;
> +		return (ipehr >> 23) == 0x1c;
>  	} else {
>  		ipehr &= ~MI_SEMAPHORE_SYNC_MASK;
>  		return ipehr == (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE |
> @@ -2798,19 +2793,20 @@ ipehr_is_semaphore_wait(struct drm_device *dev, u32 ipehr)
>  }
>  
>  static struct intel_engine_cs *
> -semaphore_wait_to_signaller_ring(struct intel_engine_cs *ring, u32 ipehr)
> +semaphore_wait_to_signaller_ring(struct intel_engine_cs *ring, u32 ipehr, u64 offset)
>  {
>  	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>  	struct intel_engine_cs *signaller;
>  	int i;
>  
>  	if (INTEL_INFO(dev_priv->dev)->gen >= 8) {
> -		/*
> -		 * FIXME: gen8 semaphore support - currently we don't emit
> -		 * semaphores on bdw anyway, but this needs to be addressed when
> -		 * we merge that code.
> -		 */
> -		return NULL;
> +		for_each_ring(signaller, dev_priv, i) {
> +			if (ring == signaller)
> +				continue;
> +
> +			if (offset == signaller->semaphore.signal_ggtt[ring->id])
> +				return signaller;
> +		}
>  	} else {
>  		u32 sync_bits = ipehr & MI_SEMAPHORE_SYNC_MASK;
>  
> @@ -2823,8 +2819,8 @@ semaphore_wait_to_signaller_ring(struct intel_engine_cs *ring, u32 ipehr)
>  		}
>  	}
>  
> -	DRM_ERROR("No signaller ring found for ring %i, ipehr 0x%08x\n",
> -		  ring->id, ipehr);
> +	DRM_ERROR("No signaller ring found for ring %i, ipehr 0x%08x, offset 0x%0%016llx\n",

The format string has a spurious 0% here. I've dropped it.
-Daniel

> +		  ring->id, ipehr, offset);
>  
>  	return NULL;
>  }
> @@ -2834,7 +2830,8 @@ semaphore_waits_for(struct intel_engine_cs *ring, u32 *seqno)
>  {
>  	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>  	u32 cmd, ipehr, head;
> -	int i;
> +	u64 offset = 0;
> +	int i, backwards;
>  
>  	ipehr = I915_READ(RING_IPEHR(ring->mmio_base));
>  	if (!ipehr_is_semaphore_wait(ring->dev, ipehr))
> @@ -2843,13 +2840,15 @@ semaphore_waits_for(struct intel_engine_cs *ring, u32 *seqno)
>  	/*
>  	 * HEAD is likely pointing to the dword after the actual command,
>  	 * so scan backwards until we find the MBOX. But limit it to just 3
> -	 * dwords. Note that we don't care about ACTHD here since that might
> +	 * or 4 dwords depending on the semaphore wait command size.
> +	 * Note that we don't care about ACTHD here since that might
>  	 * point at at batch, and semaphores are always emitted into the
>  	 * ringbuffer itself.
>  	 */
>  	head = I915_READ_HEAD(ring) & HEAD_ADDR;
> +	backwards = (INTEL_INFO(ring->dev)->gen >= 8) ? 5 : 4;
>  
> -	for (i = 4; i; --i) {
> +	for (i = backwards; i; --i) {
>  		/*
>  		 * Be paranoid and presume the hw has gone off into the wild -
>  		 * our ring is smaller than what the hardware (and hence
> @@ -2869,7 +2868,12 @@ semaphore_waits_for(struct intel_engine_cs *ring, u32 *seqno)
>  		return NULL;
>  
>  	*seqno = ioread32(ring->buffer->virtual_start + head + 4) + 1;
> -	return semaphore_wait_to_signaller_ring(ring, ipehr);
> +	if (INTEL_INFO(ring->dev)->gen >= 8) {
> +		offset = ioread32(ring->buffer->virtual_start + head + 12);
> +		offset <<= 32;
> +		offset = ioread32(ring->buffer->virtual_start + head + 8);
> +	}
> +	return semaphore_wait_to_signaller_ring(ring, ipehr, offset);
>  }
>  
>  static int semaphore_passed(struct intel_engine_cs *ring)
> -- 
> 1.9.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch