[Mesa-dev] [PATCH 23/34] i965: Add logic for allocating BO with CCS

[Pohjolainen, Topi]

On Mon, Jan 23, 2017 at 10:21:46PM -0800, Ben Widawsky wrote:
> This patch provides the support (and comments) for allocating the BO
> with space for the CCS buffer just underneath it.
> 
> This patch was originally titled:
> "i965: Create correctly sized mcs for an image"
> 
> In order to make things more bisectable, reviewable, and to have the
> CCS_MODIFIER token saved for the last patch, this patch now does less so
> it was renamed.
> 
> v2: Leave "image+mod" (Topi)
> 
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> Acked-by: Daniel Stone <daniels at collabora.com>
> Reviewed-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> ---
>  src/mesa/drivers/dri/i965/intel_screen.c | 34 ++++++++++++++++++++++++++++----
>  1 file changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
> index 8ec33ce5df..971013f2dd 100644
> --- a/src/mesa/drivers/dri/i965/intel_screen.c
> +++ b/src/mesa/drivers/dri/i965/intel_screen.c
> @@ -607,6 +607,7 @@ create_image_with_modifier(struct intel_screen *screen,
>     uint32_t requested_tiling = 0, tiling = I915_TILING_X;
>     unsigned long pitch;
>     unsigned tiled_height = 0;
> +   unsigned ccs_height = 0;
>  
>     switch (modifier) {
>     case I915_FORMAT_MOD_Y_TILED:
> @@ -628,9 +629,33 @@ create_image_with_modifier(struct intel_screen *screen,
>        break;
>     }
>  
> -   image->bo = drm_intel_bo_alloc_tiled(screen->bufmgr, "image+mod",
> -                                        width, tiled_height, cpp, &tiling,
> -                                        &pitch, 0);
> +   /*
> +    * CCS width is always going to be less than or equal to the image's width.
> +    * All we need to do is make sure we add extra rows (height) for the CCS.
> +    *
> +    * A pair of CCS bits correspond to 8x4 pixels, and must be cacheline
> +    * granularity. Each CCS tile is laid out in 8b strips, which corresponds to
> +    * 1024x512 pixel region. In memory, it looks like the following:
> +    *
> +    * ?????????????????????????????????????????????????????????
> +    * ???                 ???
> +    * ???                 ???
> +    * ???                 ???
> +    * ???      Image      ???
> +    * ???                 ???
> +    * ???                 ???
> +    * ???xxxxxxxxxxxxxxxxx???
> +    * ?????????????????????????????????????????????????????????
> +    * ???     ???           |
> +    * ???ccs  ???  unused   |
> +    * ?????????????????????-----------???
> +    * <------pitch------>
> +    */
> +   cpp = _mesa_get_format_bytes(image->format);
> +   image->bo = drm_intel_bo_alloc_tiled(screen->bufmgr,
> +                                        ccs_height ? "image+ccs" : "image+mod",
> +                                        width, tiled_height + ccs_height,
> +                                        cpp, &tiling, &pitch, 0);
>     if (image->bo == NULL)
>        return false;
>  
> @@ -647,7 +672,8 @@ create_image_with_modifier(struct intel_screen *screen,
>     if (image->planar_format)
>        assert(image->planar_format->nplanes == 1);
>  
> -   image->aux_offset = 0; /* y_tiled_height * pitch; */
> +   if (ccs_height)
> +      image->aux_offset = tiled_height * pitch /* + mt->offset */;

I think it would be clearer to drop the comment about mt->offset and
assert here also. How do you feel?

      if (ccs_height) {
         assert(mt->offset == 0);
         image->aux_offset = tiled_height * pitch;
      }

>  
>     return true;
>  }
> -- 
> 2.11.0
> 
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