Re: [PATCH] drm/i915: Don't set a MBZ bit in gen2/3 MI_FLUSH

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Apr 18, 2012 at 10:25:05AM +0100, Chris Wilson wrote:
> On gen2 and gen4, MI_EXE_FLUSH is actually an AGP flush bit and is
> documented as being must-be-zero. So obey the documentation, and separate
> the gen2 flush into its own little routine and share with gen3.

MI_EXE_FLUSH on gen4 is actually to invalidate state/instruction caches.

> This means that we can rename the existing render_ring_flush() to
> reflect the generation from which it first applies and remove the code
> for handling earlier generations from it.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

... and it doesn't compile too well here, too ;-)
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c |   53 ++++++++++++++++++++++---------
>  1 file changed, 38 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 04330e3..9c6a937 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -53,9 +53,35 @@ static inline int ring_space(struct intel_ring_buffer *ring)
>  }
>  
>  static int
> -render_ring_flush(struct intel_ring_buffer *ring,
> -		  u32	invalidate_domains,
> -		  u32	flush_domains)
> +gen2_render_ring_flush(struct intel_ring_buffer *ring,
> +		       u32	invalidate_domains,
> +		       u32	flush_domains)
> +{
> +	u32 cmd;
> +	int ret;
> +
> +	cmd = MI_FLUSH;
> +	if ((flush_domains & I915_GEM_DOMAIN_RENDER) == 0)
> +		cmd |= MI_NO_WRITE_FLUSH;
> +
> +	if (invalidate_domains & I915_GEM_DOMAIN_SAMPLER)
> +		cmd |= MI_READ_FLUSH;
> +
> +	ret = intel_ring_begin(ring, 2);
> +	if (ret)
> +		return ret;
> +
> +	intel_ring_emit(ring, cmd);
> +	intel_ring_emit(ring, MI_NOOP);
> +	intel_ring_advance(ring);
> +
> +	return 0;
> +}
> +
> +static int
> +gen4_render_ring_flush(struct intel_ring_buffer *ring,
> +		       u32	invalidate_domains,
> +		       u32	flush_domains)
>  {
>  	struct drm_device *dev = ring->dev;
>  	u32 cmd;
> @@ -90,17 +116,8 @@ render_ring_flush(struct intel_ring_buffer *ring,
>  	 */
>  
>  	cmd = MI_FLUSH | MI_NO_WRITE_FLUSH;
> -	if ((invalidate_domains|flush_domains) &
> -	    I915_GEM_DOMAIN_RENDER)
> +	if ((invalidate_domains|flush_domains) & I915_GEM_DOMAIN_RENDER)
>  		cmd &= ~MI_NO_WRITE_FLUSH;
> -	if (INTEL_INFO(dev)->gen < 4) {
> -		/*
> -		 * On the 965, the sampler cache always gets flushed
> -		 * and this bit is reserved.
> -		 */
> -		if (invalidate_domains & I915_GEM_DOMAIN_SAMPLER)
> -			cmd |= MI_READ_FLUSH;
> -	}
>  	if (invalidate_domains & I915_GEM_DOMAIN_INSTRUCTION)
>  		cmd |= MI_EXE_FLUSH;
>  
> @@ -1295,7 +1312,10 @@ int intel_init_render_ring_buffer(struct drm_device *dev)
>  		ring->irq_enable_mask = GT_USER_INTERRUPT | GT_PIPE_NOTIFY;
>  	} else {
>  		ring->add_request = i9xx_add_request;
> -		ring->flush = render_ring_flush;
> +		if (INTEL_INFO(dev)->gen < 4)
> +			ring->flush = gen2_render_ring_flush;
> +		else
> +			ring->flush = gen4_render_ring_flush;
>  		ring->get_seqno = ring_get_seqno;
>  		ring->irq_get = i9xx_ring_get_irq;
>  		ring->irq_put = i9xx_ring_put_irq;
> @@ -1340,7 +1360,10 @@ int intel_render_ring_init_dri(struct drm_device *dev, u64 start, u32 size)
>  	 * gem_init ioctl returns with -ENODEV). Hence we do not need to set up
>  	 * the special gen5 functions. */
>  	ring->add_request = i9xx_add_request;
> -	ring->flush = render_ring_flush;
> +	if (INTEL_INFO(dev)->gen < 4)
> +		ring->flush = gen2_render_ring_flush;
> +	else
> +		ring->flush = gen4_render_ring_flush;
>  	ring->get_seqno = ring_get_seqno;
>  	ring->irq_get = i9xx_ring_get_irq;
>  	ring->irq_put = i9xx_ring_put_irq;
> -- 
> 1.7.10
> 
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-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48