[Mesa-dev] [PATCH 06/12] panfrost: Refactor layout selection (BO creation)

[Tomeu Vizoso]

On Sun, 10 Mar 2019 at 07:50, Alyssa Rosenzweig <alyssa at rosenzweig.io> wrote:
>
> With a unified layout field, we can specify the logic for BO layout
> explicitly, deciding between linear/tiled/AFBC based on the specified
> usage/binding flags.
>
> Signed-off-by: Alyssa Rosenzweig <alyssa at rosenzweig.io>

Great stuff!

Reviewed-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>

> ---
>  src/gallium/drivers/panfrost/pan_resource.c | 64 ++++++++++++++-------
>  1 file changed, 44 insertions(+), 20 deletions(-)
>
> diff --git a/src/gallium/drivers/panfrost/pan_resource.c b/src/gallium/drivers/panfrost/pan_resource.c
> index 0cebbdb6e51..39783f5a63a 100644
> --- a/src/gallium/drivers/panfrost/pan_resource.c
> +++ b/src/gallium/drivers/panfrost/pan_resource.c
> @@ -181,6 +181,48 @@ panfrost_surface_destroy(struct pipe_context *pipe,
>          free(surf);
>  }
>
> +/* Based on the usage, figure out what storing will be used. There are
> + * various tradeoffs:
> + *
> + * Linear: the basic format, bad for memory bandwidth, bad for cache
> + * use. Zero-copy, though. Renderable.
> + *
> + * Tiled: Not compressed, but cache-optimized. Expensive to write into
> + * (due to software tiling), but cheap to sample from. Ideal for most
> + * textures.
> + *
> + * AFBC: Compressed and renderable (so always desirable for non-scanout
> + * rendertargets). Cheap to sample from. The format is black box, so we
> + * can't read/write from software.
> + */
> +
> +static enum panfrost_memory_layout
> +panfrost_best_layout(const struct pipe_resource *rsrc)
> +{
> +        /* For streaming, optimize for CPU write since it's one-use */
> +
> +        if (rsrc->usage == PIPE_USAGE_STREAM)
> +                return PAN_LINEAR;
> +
> +        /* Legal formats depends if we're renderable */
> +
> +        unsigned renderable_bind =
> +                PIPE_BIND_DEPTH_STENCIL |
> +                PIPE_BIND_RENDER_TARGET |
> +                PIPE_BIND_BLENDABLE;
> +
> +        if (rsrc->bind & renderable_bind) {
> +                /* TODO: AFBC */
> +                return PAN_LINEAR;
> +        } else if (rsrc->bind & PIPE_BIND_SAMPLER_VIEW) {
> +                return PAN_TILED;
> +        }
> +
> +        /* If all else fails, we default to linear */
> +
> +        return PAN_LINEAR;
> +}
> +
>  static struct panfrost_bo *
>  panfrost_create_bo(struct panfrost_screen *screen, const struct pipe_resource *template)
>  {
> @@ -195,26 +237,8 @@ panfrost_create_bo(struct panfrost_screen *screen, const struct pipe_resource *t
>          if (template->height0) sz *= template->height0;
>          if (template->depth0) sz *= template->depth0;
>
> -        /* Based on the usage, figure out what storing will be used. There are
> -         * various tradeoffs:
> -         *
> -         * Linear: the basic format, bad for memory bandwidth, bad for cache
> -         * use. Zero-copy, though. Renderable.
> -         *
> -         * Tiled: Not compressed, but cache-optimized. Expensive to write into
> -         * (due to software tiling), but cheap to sample from. Ideal for most
> -         * textures.
> -         *
> -         * AFBC: Compressed and renderable (so always desirable for non-scanout
> -         * rendertargets). Cheap to sample from. The format is black box, so we
> -         * can't read/write from software.
> -         */
> -
> -        /* Tiling textures is almost always faster, unless we only use it once */
> -        bool should_tile = (template->usage != PIPE_USAGE_STREAM) && (template->bind & PIPE_BIND_SAMPLER_VIEW);
> -
> -        /* Set the layout appropriately */
> -        bo->layout = should_tile ? PAN_TILED : PAN_LINEAR;
> +        bo->imported_size = sz;
> +        bo->layout = panfrost_best_layout(template);
>
>          if (bo->layout == PAN_TILED) {
>                  /* For tiled, we don't map directly, so just malloc any old buffer */
> --
> 2.20.1
>
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