/* * Copyright (C) 2019 Collabora * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * * Authors: * Alyssa Rosenzweig */ #include "pan_resource.h" #include "util/u_format.h" /* Arm FrameBuffer Compression (AFBC) is a lossless compression scheme natively * implemented in Mali GPUs (as well as many display controllers paired with * Mali GPUs, etc). Where possible, Panfrost prefers to use AFBC for both * rendering and texturing. In most cases, this is a performance-win due to a * dramatic reduction in memory bandwidth and cache locality compared to a * linear resources. * * AFBC divides the framebuffer into 16x16 tiles (other sizes possible, TODO: * do we need to support this?). So, the width and height each must be aligned * up to 16 pixels. This is inherently good for performance; note that for a 4 * byte-per-pixel format like RGBA8888, that means that rows are 16*4=64 byte * aligned, which is the cache-line size. * * For each AFBC-compressed resource, there is a single contiguous * (CPU/GPU-shared) buffer. This buffer itself is divided into two parts: * header and body, placed immediately after each other. * * The AFBC header contains 16 bytes of metadata per tile. * * The AFBC body is the same size as the original linear resource (padded to * the nearest tile). Although the body comes immediately after the header, it * must also be cache-line aligned, so there can sometimes be a bit of padding * between the header and body. * * As an example, a 64x64 RGBA framebuffer contains 64/16 = 4 tiles horizontally and * 4 tiles vertically. There are 4*4=16 tiles in total, each containing 16 * bytes of metadata, so there is a 16*16=256 byte header. 64x64 is already * tile aligned, so the body is 64*64 * 4 bytes per pixel = 16384 bytes of * body. * * From userspace, Panfrost needs to be able to calculate these sizes. It * explicitly does not and can not know the format of the data contained within * this header and body. The GPU has native support for AFBC encode/decode. For * an internal FBO or a framebuffer used for scanout with an AFBC-compatible * winsys/display-controller, the buffer is maintained AFBC throughout flight, * and the driver never needs to know the internal data. For edge cases where * the driver really does need to read/write from the AFBC resource, we * generate a linear staging buffer and use the GPU to blit AFBC<--->linear. * TODO: Implement me. */ #define AFBC_TILE_WIDTH 16 #define AFBC_TILE_HEIGHT 16 #define AFBC_HEADER_BYTES_PER_TILE 16 #define AFBC_CACHE_ALIGN 64 /* Is it possible to AFBC compress a particular format? Common formats (and * YUV) are compressible. Some obscure formats are not and fallback on linear, * at a performance hit. Also, if you need to disable AFBC entirely in the * driver for debug/profiling, just always return false here. */ bool panfrost_format_supports_afbc(enum pipe_format format) { const struct util_format_description *desc = util_format_description(format); if (util_format_is_rgba8_variant(desc)) return true; if (format == PIPE_FORMAT_Z32_UNORM) return true; /* TODO: AFBC of other formats */ return false; } /* AFBC is enabled on a per-resource basis (AFBC enabling is theoretically * indepdent between color buffers and depth/stencil). To enable, we allocate * the AFBC metadata buffer and mark that it is enabled. We do -not- actually * edit the fragment job here. This routine should be called ONCE per * AFBC-compressed buffer, rather than on every frame. */ void panfrost_enable_afbc(struct panfrost_context *ctx, struct panfrost_resource *rsrc, bool ds) { struct pipe_context *gallium = (struct pipe_context *) ctx; struct panfrost_screen *screen = pan_screen(gallium->screen); unsigned width = rsrc->base.width0; unsigned height = rsrc->base.height0; unsigned bytes_per_pixel = util_format_get_blocksize(rsrc->base.format); /* Align to tile */ unsigned aligned_width = ALIGN(width, AFBC_TILE_WIDTH); unsigned aligned_height = ALIGN(height, AFBC_TILE_HEIGHT); /* Compute size in tiles, rather than pixels */ unsigned tile_count_x = aligned_width / AFBC_TILE_WIDTH; unsigned tile_count_y = aligned_height / AFBC_TILE_HEIGHT; unsigned tile_count = tile_count_x * tile_count_y; unsigned header_bytes = tile_count * AFBC_HEADER_BYTES_PER_TILE; unsigned header_size = ALIGN(header_bytes, AFBC_CACHE_ALIGN); /* The stride is a normal stride, but aligned */ unsigned unaligned_stride = aligned_width * bytes_per_pixel; unsigned stride = ALIGN(unaligned_stride, AFBC_CACHE_ALIGN); /* Compute the entire buffer size */ unsigned body_size = stride * aligned_height; unsigned buffer_size = header_size + body_size; /* Allocate the AFBC slab itself, large enough to hold the above */ screen->driver->allocate_slab(screen, &rsrc->bo->afbc_slab, ALIGN(buffer_size, 4096) / 4096, true, 0, 0, 0); /* Compressed textured reads use a tagged pointer to the metadata */ rsrc->bo->layout = PAN_AFBC; rsrc->bo->gpu = rsrc->bo->afbc_slab.gpu | (ds ? 0 : 1); rsrc->bo->cpu = rsrc->bo->afbc_slab.cpu; rsrc->bo->gem_handle = rsrc->bo->afbc_slab.gem_handle; rsrc->bo->afbc_metadata_size = header_size; }