Re: [PATCH] drm/i915: Apply post-sync write for pipe control invalidates

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Apply post-sync write for pipe control invalidates
Date: Fri, 10 Aug 2012 12:57:59 +0300	[thread overview]
Message-ID: <87d32zjcgo.fsf@intel.com> (raw)
In-Reply-To: <1344590290-5206-1-git-send-email-chris@chris-wilson.co.uk>

On Fri, 10 Aug 2012, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> When invalidating the TLBs it is documentated as requiring a post-sync
> write. Failure to do so seems to result in a GPU hang.
>
> Exposure to this hang on IVB seems to be a result of removing the extra
> stalls required for SNB pipecontrol workarounds:

Hi Chris, AFAICT TLB invalidate requires PIPE_CONTROL_CS_STALL set per
the spec. I can't find a mention of the post-sync write, though. Could
you double check, please?

BR,
Jani.

>
> commit 6c6cf5aa9c583478b19e23149feaa92d01fb8c2d
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date:   Fri Jul 20 18:02:28 2012 +0100
>
>     drm/i915: Only apply the SNB pipe control w/a to gen6
>
> Reported-by: yex.tian@intel.com
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=53322
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c |   35 ++++++++++++++++++-------------
>  1 file changed, 21 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 13318a0..7608bc2 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -213,20 +213,27 @@ gen6_render_ring_flush(struct intel_ring_buffer *ring,
>  	 * number of bits based on the write domains has little performance
>  	 * impact.
>  	 */
> -	flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
> -	flags |= PIPE_CONTROL_TLB_INVALIDATE;
> -	flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
> -	flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
> -	flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
> -	flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
> -	flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
> -	flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
> -	/*
> -	 * Ensure that any following seqno writes only happen when the render
> -	 * cache is indeed flushed (but only if the caller actually wants that).
> -	 */
> -	if (flush_domains)
> +	if (flush_domains) {
> +		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
> +		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
> +		/*
> +		 * Ensure that any following seqno writes only happen
> +		 * when the render cache is indeed flushed.
> +		 */
>  		flags |= PIPE_CONTROL_CS_STALL;
> +	}
> +	if (invalidate_domains) {
> +		flags |= PIPE_CONTROL_TLB_INVALIDATE;
> +		flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
> +		flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
> +		flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
> +		flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
> +		flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
> +		/*
> +		 * TLB invalidate requires a post-sync write.
> +		 */
> +		flags |= PIPE_CONTROL_QW_WRITE;
> +	}
>  
>  	ret = intel_ring_begin(ring, 4);
>  	if (ret)
> @@ -234,7 +241,7 @@ gen6_render_ring_flush(struct intel_ring_buffer *ring,
>  
>  	intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
>  	intel_ring_emit(ring, flags);
> -	intel_ring_emit(ring, 0);
> +	intel_ring_emit(ring, (u32)ring->status_page.gfx_addr+2048);
>  	intel_ring_emit(ring, 0);
>  	intel_ring_advance(ring);
>  
> -- 
> 1.7.10.4
>
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