hk: eliminate null_sink

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35797>

src/asahi/vulkan/hk_cmd_draw.c

@@ -3047,7 +3047,7 @@ hk_flush_dynamic_state(struct hk_cmd_buffer *cmd, struct hk_cs *cs,
           */
          desc->root.draw.vertex_output_buffer =
             vb_size ? hk_pool_alloc(cmd, vb_size, 4).gpu
-                    : dev->rodata.null_sink;
+                    : AGX_SCRATCH_PAGE_ADDRESS;
       }
    }
 

src/asahi/vulkan/hk_device.c

@@ -102,14 +102,6 @@ hk_upload_rodata(struct hk_device *dev)
    dev->rodata.heap = dev->rodata.bo->va->addr + offs;
    offs += sizeof(struct agx_heap);
 
-   /* For null storage descriptors, we need to reserve 16 bytes to catch writes.
-    * No particular content is required; we cannot get robustness2 semantics
-    * without more work.
-    */
-   offs = align(offs, 16);
-   dev->rodata.null_sink = dev->rodata.bo->va->addr + offs;
-   offs += 16;
-
    return VK_SUCCESS;
 }
 

src/asahi/vulkan/hk_device.h

@@ -84,7 +84,6 @@ struct hk_device {
    struct {
       struct agx_bo *bo;
       uint64_t image_heap_ptr;
-      uint64_t null_sink;
       uint64_t heap;
    } rodata;