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

[Alyssa Rosenzweig]

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>
---
 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