[Intel-gfx] [PATCH 29/43] drm/i915/bdw: Write the tail pointer, LRC style

[Damien Lespiau]

On Thu, Jul 24, 2014 at 05:04:37PM +0100, Thomas Daniel wrote:
> From: Oscar Mateo <oscar.mateo at intel.com>
> 
> Each logical ring context has the tail pointer in the context object,
> so update it before submission.
> 
> v2: New namespace.

I believe we could just leave the context object mapped for its whole
lifetime. Something to thing about at a later point.

-- 
Damien

> Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_lrc.c |   19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 535ef98..5b6f416 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -176,6 +176,21 @@ static void execlists_elsp_write(struct intel_engine_cs *ring,
>  	gen6_gt_force_wake_put(dev_priv, FORCEWAKE_ALL);
>  }
>  
> +static int execlists_ctx_write_tail(struct drm_i915_gem_object *ctx_obj, u32 tail)
> +{
> +	struct page *page;
> +	uint32_t *reg_state;
> +
> +	page = i915_gem_object_get_page(ctx_obj, 1);
> +	reg_state = kmap_atomic(page);
> +
> +	reg_state[CTX_RING_TAIL+1] = tail;
> +
> +	kunmap_atomic(reg_state);
> +
> +	return 0;
> +}
> +
>  static int execlists_submit_context(struct intel_engine_cs *ring,
>  				    struct intel_context *to0, u32 tail0,
>  				    struct intel_context *to1, u32 tail1)
> @@ -187,10 +202,14 @@ static int execlists_submit_context(struct intel_engine_cs *ring,
>  	BUG_ON(!ctx_obj0);
>  	BUG_ON(!i915_gem_obj_is_pinned(ctx_obj0));
>  
> +	execlists_ctx_write_tail(ctx_obj0, tail0);
> +
>  	if (to1) {
>  		ctx_obj1 = to1->engine[ring->id].state;
>  		BUG_ON(!ctx_obj1);
>  		BUG_ON(!i915_gem_obj_is_pinned(ctx_obj1));
> +
> +		execlists_ctx_write_tail(ctx_obj1, tail1);
>  	}
>  
>  	execlists_elsp_write(ring, ctx_obj0, ctx_obj1);
> -- 
> 1.7.9.5
> 
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