Re: [Intel gfx][i-g-t PATCH 3/4] rendercopy/bdw: A workaround for 3D pipeline

[Damien Lespiau <damien.lespiau@intel.com>]

On Fri, Dec 06, 2013 at 04:54:46PM +0800, Xiang, Haihao wrote:
> From: "Xiang, Haihao" <haihao.xiang@intel.com>
> 
> Emit PIPELINE_SELECT twice and make sure the commands in
> the first batch buffer have been done.
> 
> However I don't know why this works !!!

Hum :) on one hand, it's great that you found this w/a, on the other
hand, I'm not comfortable with not understanding why this works. So far
what we know (I don't have Silicon that can't test anything):

 - Ken was saying that mesa doesn't need this.
 - There are a bunch of W/A around FF units clock gating, might worth
   checking that we're not hiting WaDisableFfDopClockGating or one of
   those 3D Vs GPGPU pipelines ones.
   This could happen to you but not to Ken because you have been
   switching between 3D and media pipeline with the 2 igt tests.
 - In any case, doing a pass on the W/A sounds like a good idea
 - I'd be interested to know if there a even more minimal batch that
   works (say an empty batch), or if the active ingredient is the
   pipeline switch.

If people want to push the patch to make progress on other parts, I
guess that's fine, but we'll need to dig deeper here.

-- 
Damien

> 
> Signed-off-by: Xiang, Haihao <haihao.xiang@intel.com>
> ---
>  lib/rendercopy_gen8.c |   19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/rendercopy_gen8.c b/lib/rendercopy_gen8.c
> index 1a137dd..6eb1051 100644
> --- a/lib/rendercopy_gen8.c
> +++ b/lib/rendercopy_gen8.c
> @@ -148,7 +148,8 @@ batch_copy(struct intel_batchbuffer *batch, const void *ptr, uint32_t size, uint
>  
>  static void
>  gen6_render_flush(struct intel_batchbuffer *batch,
> -		  drm_intel_context *context, uint32_t batch_end)
> +		drm_intel_context *context, uint32_t batch_end,
> +		int waiting)
>  {
>  	int ret;
>  
> @@ -157,6 +158,11 @@ gen6_render_flush(struct intel_batchbuffer *batch,
>  		ret = drm_intel_gem_bo_context_exec(batch->bo, context,
>  						    batch_end, 0);
>  	assert(ret == 0);
> +
> +	if (waiting) {
> +		dri_bo_map(batch->bo, 0);
> +		dri_bo_unmap(batch->bo);
> +	}
>  }
>  
>  /* Mostly copy+paste from gen6, except height, width, pitch moved */
> @@ -880,6 +886,15 @@ void gen8_render_copyfunc(struct intel_batchbuffer *batch,
>  
>  	intel_batchbuffer_flush_with_context(batch, context);
>  
> +	/* I don't know why it works !!! */
> +	batch->ptr = batch->buffer;
> +	OUT_BATCH(GEN6_PIPELINE_SELECT | PIPELINE_SELECT_3D);
> +	OUT_BATCH(MI_BATCH_BUFFER_END);
> +	batch_end = batch_align(batch, 8);
> +	assert(batch_end < BATCH_STATE_SPLIT);
> +	gen6_render_flush(batch, context, batch_end, 1);
> +	intel_batchbuffer_reset(batch);
> +
>  	batch_align(batch, 8);
>  
>  	batch->ptr = &batch->buffer[BATCH_STATE_SPLIT];
> @@ -968,6 +983,6 @@ void gen8_render_copyfunc(struct intel_batchbuffer *batch,
>  
>  	annotation_flush(&aub_annotations, batch);
>  
> -	gen6_render_flush(batch, context, batch_end);
> +	gen6_render_flush(batch, context, batch_end, 0);
>  	intel_batchbuffer_reset(batch);
>  }
> -- 
> 1.7.9.5
> 
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