Re: [PATCH 08/13] drm/i915: Implement MI decode for gen8

[Ben Widawsky <ben@bwidawsk.net>]

On Wed, Apr 30, 2014 at 02:21:15PM +0300, Ville Syrjälä wrote:
> On Tue, Apr 29, 2014 at 02:52:35PM -0700, Ben Widawsky wrote:
> > From: Ben Widawsky <benjamin.widawsky@linux.intel.com>
> > 
> > This is needed to implement ipehr_is_semaphore_wait
> > 
> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> >  drivers/gpu/drm/i915/i915_irq.c | 11 +++++------
> >  1 file changed, 5 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 2d76183..bfd21c7 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -2561,12 +2561,9 @@ 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;
> > +		/* Broadwell's semaphore wait is 3 dwords. We hope IPEHR is the
> > +		 * first dword. */
> > +		return (ipehr >> 23) == 0x1c;
> >  	} else {
> >  		ipehr &= ~MI_SEMAPHORE_SYNC_MASK;
> >  		return ipehr == (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE |
> > @@ -2586,6 +2583,8 @@ semaphore_wait_to_signaller_ring(struct intel_ring_buffer *ring, u32 ipehr)
> >  		 * FIXME: gen8 semaphore support - currently we don't emit
> >  		 * semaphores on bdw anyway, but this needs to be addressed when
> >  		 * we merge that code.
> > +		 *
> > +		 * XXX: Gen8 needs more than just IPEHR.
> >  		 */
> 
> I believe something like this should take care of the remaining gap.
> 

Thanks for the help. At this point I just want to get the damn thing
merged, and want to avoid any extra risk. Would you mind resending this
as a distinct patch (authored by you), after we get the rest merged?

> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 2446e61..cd1069e 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2590,19 +2590,21 @@ ipehr_is_semaphore_wait(struct drm_device *dev, u32 ipehr)
>  }
>  
>  static struct intel_ring_buffer *
> -semaphore_wait_to_signaller_ring(struct intel_ring_buffer *ring, u32 ipehr)
> +semaphore_wait_to_signaller_ring(struct intel_ring_buffer *ring,
> +				 u32 ipehr, u64 offset)
>  {
>  	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>  	struct intel_ring_buffer *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_gtt[ring->id])
> +				return signaller;
> +		}
>  	} else {
>  		u32 sync_bits = ipehr & MI_SEMAPHORE_SYNC_MASK;
>  
> @@ -2627,6 +2629,7 @@ semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
>  {
>  	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>  	u32 cmd, ipehr, head;
> +	u64 offset = 0;
>  	int i;
>  
>  	ipehr = I915_READ(RING_IPEHR(ring->mmio_base));
> @@ -2662,7 +2665,12 @@ semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
>  		return NULL;
>  
>  	*seqno = ioread32(ring->virtual_start + head + 4) + 1;
> -	return semaphore_wait_to_signaller_ring(ring, ipehr);
> +	if (INTEL_INFO(dev_priv->dev)->gen >= 8) {
> +		offset = ioread32(ring->virtual_start + head + 12);
> +		offset <<= 32;
> +		offset |= ioread32(ring->virtual_start + head + 8);
> +	}
> +	return semaphore_wait_to_signaller_ring(ring, ipehr, offset);
>  }
>  
>  static int semaphore_passed(struct intel_ring_buffer *ring)
> -- 
> 1.8.3.2
> 
> 
> >  		return NULL;
> >  	} else {
> > -- 
> > 1.9.2
> > 
> > _______________________________________________
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> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ben Widawsky, Intel Open Source Technology Center
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