drivers/gpu/drm/ttm/ttm_bo_util.c

   1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
   2 /**************************************************************************
   3  *
   4  * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
   5  * All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the
   9  * "Software"), to deal in the Software without restriction, including
  10  * without limitation the rights to use, copy, modify, merge, publish,
  11  * distribute, sub license, and/or sell copies of the Software, and to
  12  * permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the
  16  * next paragraph) shall be included in all copies or substantial portions
  17  * of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  22  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  23  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  24  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  25  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  **************************************************************************/
  28 /*
  29  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  30  */
  31
  32 #include <drm/ttm/ttm_bo_driver.h>
  33 #include <drm/ttm/ttm_placement.h>
  34 #include <drm/drm_vma_manager.h>
  35 #include <linux/io.h>
  36 #include <linux/highmem.h>
  37 #include <linux/wait.h>
  38 #include <linux/slab.h>
  39 #include <linux/vmalloc.h>
  40 #include <linux/module.h>
  41 #include <linux/dma-resv.h>
  42
  43 struct ttm_transfer_obj {
  44         struct ttm_buffer_object base;
  45         struct ttm_buffer_object *bo;
  46 };
  47
  48 void ttm_bo_free_old_node(struct ttm_buffer_object *bo)
  49 {
  50         ttm_resource_free(bo, &bo->mem);
  51 }
  52
  53 int ttm_bo_move_ttm(struct ttm_buffer_object *bo,
  54                    struct ttm_operation_ctx *ctx,
  55                     struct ttm_resource *new_mem)
  56 {
  57         struct ttm_tt *ttm = bo->ttm;
  58         struct ttm_resource *old_mem = &bo->mem;
  59         int ret;
  60
  61         if (old_mem->mem_type != TTM_PL_SYSTEM) {
  62                 ret = ttm_bo_wait(bo, ctx->interruptible, ctx->no_wait_gpu);
  63
  64                 if (unlikely(ret != 0)) {
  65                         if (ret != -ERESTARTSYS)
  66                                 pr_err("Failed to expire sync object before unbinding TTM\n");
  67                         return ret;
  68                 }
  69
  70                 ttm_tt_unbind(bo->bdev, ttm);
  71                 ttm_bo_free_old_node(bo);
  72                 old_mem->mem_type = TTM_PL_SYSTEM;
  73         }
  74
  75         ret = ttm_tt_set_placement_caching(ttm, new_mem->placement);
  76         if (unlikely(ret != 0))
  77                 return ret;
  78
  79         if (new_mem->mem_type != TTM_PL_SYSTEM) {
  80                 ret = ttm_tt_bind(bo->bdev, ttm, new_mem, ctx);
  81                 if (unlikely(ret != 0))
  82                         return ret;
  83         }
  84
  85         *old_mem = *new_mem;
  86         new_mem->mm_node = NULL;
  87
  88         return 0;
  89 }
  90 EXPORT_SYMBOL(ttm_bo_move_ttm);
  91
  92 int ttm_mem_io_reserve(struct ttm_bo_device *bdev,
  93                        struct ttm_resource *mem)
  94 {
  95         if (mem->bus.offset || mem->bus.addr)
  96                 return 0;
  97
  98         mem->bus.is_iomem = false;
  99         if (!bdev->driver->io_mem_reserve)
 100                 return 0;
 101
 102         return bdev->driver->io_mem_reserve(bdev, mem);
 103 }
 104
 105 void ttm_mem_io_free(struct ttm_bo_device *bdev,
 106                      struct ttm_resource *mem)
 107 {
 108         if (!mem->bus.offset && !mem->bus.addr)
 109                 return;
 110
 111         if (bdev->driver->io_mem_free)
 112                 bdev->driver->io_mem_free(bdev, mem);
 113
 114         mem->bus.offset = 0;
 115         mem->bus.addr = NULL;
 116 }
 117
 118 static int ttm_resource_ioremap(struct ttm_bo_device *bdev,
 119                                struct ttm_resource *mem,
 120                                void **virtual)
 121 {
 122         int ret;
 123         void *addr;
 124
 125         *virtual = NULL;
 126         ret = ttm_mem_io_reserve(bdev, mem);
 127         if (ret || !mem->bus.is_iomem)
 128                 return ret;
 129
 130         if (mem->bus.addr) {
 131                 addr = mem->bus.addr;
 132         } else {
 133                 size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
 134
 135                 if (mem->placement & TTM_PL_FLAG_WC)
 136                         addr = ioremap_wc(mem->bus.offset, bus_size);
 137                 else
 138                         addr = ioremap(mem->bus.offset, bus_size);
 139                 if (!addr) {
 140                         ttm_mem_io_free(bdev, mem);
 141                         return -ENOMEM;
 142                 }
 143         }
 144         *virtual = addr;
 145         return 0;
 146 }
 147
 148 static void ttm_resource_iounmap(struct ttm_bo_device *bdev,
 149                                 struct ttm_resource *mem,
 150                                 void *virtual)
 151 {
 152         if (virtual && mem->bus.addr == NULL)
 153                 iounmap(virtual);
 154         ttm_mem_io_free(bdev, mem);
 155 }
 156
 157 static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
 158 {
 159         uint32_t *dstP =
 160             (uint32_t *) ((unsigned long)dst + (page << PAGE_SHIFT));
 161         uint32_t *srcP =
 162             (uint32_t *) ((unsigned long)src + (page << PAGE_SHIFT));
 163
 164         int i;
 165         for (i = 0; i < PAGE_SIZE / sizeof(uint32_t); ++i)
 166                 iowrite32(ioread32(srcP++), dstP++);
 167         return 0;
 168 }
 169
 170 static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
 171                                 unsigned long page,
 172                                 pgprot_t prot)
 173 {
 174         struct page *d = ttm->pages[page];
 175         void *dst;
 176
 177         if (!d)
 178                 return -ENOMEM;
 179
 180         src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
 181         dst = kmap_atomic_prot(d, prot);
 182         if (!dst)
 183                 return -ENOMEM;
 184
 185         memcpy_fromio(dst, src, PAGE_SIZE);
 186
 187         kunmap_atomic(dst);
 188
 189         return 0;
 190 }
 191
 192 static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
 193                                 unsigned long page,
 194                                 pgprot_t prot)
 195 {
 196         struct page *s = ttm->pages[page];
 197         void *src;
 198
 199         if (!s)
 200                 return -ENOMEM;
 201
 202         dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
 203         src = kmap_atomic_prot(s, prot);
 204         if (!src)
 205                 return -ENOMEM;
 206
 207         memcpy_toio(dst, src, PAGE_SIZE);
 208
 209         kunmap_atomic(src);
 210
 211         return 0;
 212 }
 213
 214 int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 215                        struct ttm_operation_ctx *ctx,
 216                        struct ttm_resource *new_mem)
 217 {
 218         struct ttm_bo_device *bdev = bo->bdev;
 219         struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
 220         struct ttm_tt *ttm = bo->ttm;
 221         struct ttm_resource *old_mem = &bo->mem;
 222         struct ttm_resource old_copy = *old_mem;
 223         void *old_iomap;
 224         void *new_iomap;
 225         int ret;
 226         unsigned long i;
 227         unsigned long page;
 228         unsigned long add = 0;
 229         int dir;
 230
 231         ret = ttm_bo_wait(bo, ctx->interruptible, ctx->no_wait_gpu);
 232         if (ret)
 233                 return ret;
 234
 235         ret = ttm_resource_ioremap(bdev, old_mem, &old_iomap);
 236         if (ret)
 237                 return ret;
 238         ret = ttm_resource_ioremap(bdev, new_mem, &new_iomap);
 239         if (ret)
 240                 goto out;
 241
 242         /*
 243          * Single TTM move. NOP.
 244          */
 245         if (old_iomap == NULL && new_iomap == NULL)
 246                 goto out2;
 247
 248         /*
 249          * Don't move nonexistent data. Clear destination instead.
 250          */
 251         if (old_iomap == NULL &&
 252             (ttm == NULL || (!ttm_tt_is_populated(ttm) &&
 253                              !(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)))) {
 254                 memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
 255                 goto out2;
 256         }
 257
 258         /*
 259          * TTM might be null for moves within the same region.
 260          */
 261         if (ttm) {
 262                 ret = ttm_tt_populate(bdev, ttm, ctx);
 263                 if (ret)
 264                         goto out1;
 265         }
 266
 267         add = 0;
 268         dir = 1;
 269
 270         if ((old_mem->mem_type == new_mem->mem_type) &&
 271             (new_mem->start < old_mem->start + old_mem->size)) {
 272                 dir = -1;
 273                 add = new_mem->num_pages - 1;
 274         }
 275
 276         for (i = 0; i < new_mem->num_pages; ++i) {
 277                 page = i * dir + add;
 278                 if (old_iomap == NULL) {
 279                         pgprot_t prot = ttm_io_prot(old_mem->placement,
 280                                                     PAGE_KERNEL);
 281                         ret = ttm_copy_ttm_io_page(ttm, new_iomap, page,
 282                                                    prot);
 283                 } else if (new_iomap == NULL) {
 284                         pgprot_t prot = ttm_io_prot(new_mem->placement,
 285                                                     PAGE_KERNEL);
 286                         ret = ttm_copy_io_ttm_page(ttm, old_iomap, page,
 287                                                    prot);
 288                 } else {
 289                         ret = ttm_copy_io_page(new_iomap, old_iomap, page);
 290                 }
 291                 if (ret)
 292                         goto out1;
 293         }
 294         mb();
 295 out2:
 296         old_copy = *old_mem;
 297         *old_mem = *new_mem;
 298         new_mem->mm_node = NULL;
 299
 300         if (!man->use_tt)
 301                 ttm_bo_tt_destroy(bo);
 302
 303 out1:
 304         ttm_resource_iounmap(bdev, old_mem, new_iomap);
 305 out:
 306         ttm_resource_iounmap(bdev, &old_copy, old_iomap);
 307
 308         /*
 309          * On error, keep the mm node!
 310          */
 311         if (!ret)
 312                 ttm_resource_free(bo, &old_copy);
 313         return ret;
 314 }
 315 EXPORT_SYMBOL(ttm_bo_move_memcpy);
 316
 317 static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
 318 {
 319         struct ttm_transfer_obj *fbo;
 320
 321         fbo = container_of(bo, struct ttm_transfer_obj, base);
 322         ttm_bo_put(fbo->bo);
 323         kfree(fbo);
 324 }
 325
 326 /**
 327  * ttm_buffer_object_transfer
 328  *
 329  * @bo: A pointer to a struct ttm_buffer_object.
 330  * @new_obj: A pointer to a pointer to a newly created ttm_buffer_object,
 331  * holding the data of @bo with the old placement.
 332  *
 333  * This is a utility function that may be called after an accelerated move
 334  * has been scheduled. A new buffer object is created as a placeholder for
 335  * the old data while it's being copied. When that buffer object is idle,
 336  * it can be destroyed, releasing the space of the old placement.
 337  * Returns:
 338  * !0: Failure.
 339  */
 340
 341 static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 342                                       struct ttm_buffer_object **new_obj)
 343 {
 344         struct ttm_transfer_obj *fbo;
 345         int ret;
 346
 347         fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
 348         if (!fbo)
 349                 return -ENOMEM;
 350
 351         fbo->base = *bo;
 352         fbo->base.mem.placement |= TTM_PL_FLAG_NO_EVICT;
 353
 354         ttm_bo_get(bo);
 355         fbo->bo = bo;
 356
 357         /**
 358          * Fix up members that we shouldn't copy directly:
 359          * TODO: Explicit member copy would probably be better here.
 360          */
 361
 362         atomic_inc(&ttm_bo_glob.bo_count);
 363         INIT_LIST_HEAD(&fbo->base.ddestroy);
 364         INIT_LIST_HEAD(&fbo->base.lru);
 365         INIT_LIST_HEAD(&fbo->base.swap);
 366         fbo->base.moving = NULL;
 367         drm_vma_node_reset(&fbo->base.base.vma_node);
 368
 369         kref_init(&fbo->base.kref);
 370         fbo->base.destroy = &ttm_transfered_destroy;
 371         fbo->base.acc_size = 0;
 372         if (bo->type != ttm_bo_type_sg)
 373                 fbo->base.base.resv = &fbo->base.base._resv;
 374
 375         dma_resv_init(&fbo->base.base._resv);
 376         fbo->base.base.dev = NULL;
 377         ret = dma_resv_trylock(&fbo->base.base._resv);
 378         WARN_ON(!ret);
 379
 380         *new_obj = &fbo->base;
 381         return 0;
 382 }
 383
 384 pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
 385 {
 386         /* Cached mappings need no adjustment */
 387         if (caching_flags & TTM_PL_FLAG_CACHED)
 388                 return tmp;
 389
 390 #if defined(__i386__) || defined(__x86_64__)
 391         if (caching_flags & TTM_PL_FLAG_WC)
 392                 tmp = pgprot_writecombine(tmp);
 393         else if (boot_cpu_data.x86 > 3)
 394                 tmp = pgprot_noncached(tmp);
 395 #endif
 396 #if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
 397     defined(__powerpc__) || defined(__mips__)
 398         if (caching_flags & TTM_PL_FLAG_WC)
 399                 tmp = pgprot_writecombine(tmp);
 400         else
 401                 tmp = pgprot_noncached(tmp);
 402 #endif
 403 #if defined(__sparc__)
 404         tmp = pgprot_noncached(tmp);
 405 #endif
 406         return tmp;
 407 }
 408 EXPORT_SYMBOL(ttm_io_prot);
 409
 410 static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
 411                           unsigned long offset,
 412                           unsigned long size,
 413                           struct ttm_bo_kmap_obj *map)
 414 {
 415         struct ttm_resource *mem = &bo->mem;
 416
 417         if (bo->mem.bus.addr) {
 418                 map->bo_kmap_type = ttm_bo_map_premapped;
 419                 map->virtual = (void *)(((u8 *)bo->mem.bus.addr) + offset);
 420         } else {
 421                 map->bo_kmap_type = ttm_bo_map_iomap;
 422                 if (mem->placement & TTM_PL_FLAG_WC)
 423                         map->virtual = ioremap_wc(bo->mem.bus.offset + offset,
 424                                                   size);
 425                 else
 426                         map->virtual = ioremap(bo->mem.bus.offset + offset,
 427                                                size);
 428         }
 429         return (!map->virtual) ? -ENOMEM : 0;
 430 }
 431
 432 static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
 433                            unsigned long start_page,
 434                            unsigned long num_pages,
 435                            struct ttm_bo_kmap_obj *map)
 436 {
 437         struct ttm_resource *mem = &bo->mem;
 438         struct ttm_operation_ctx ctx = {
 439                 .interruptible = false,
 440                 .no_wait_gpu = false
 441         };
 442         struct ttm_tt *ttm = bo->ttm;
 443         pgprot_t prot;
 444         int ret;
 445
 446         BUG_ON(!ttm);
 447
 448         ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
 449         if (ret)
 450                 return ret;
 451
 452         if (num_pages == 1 && (mem->placement & TTM_PL_FLAG_CACHED)) {
 453                 /*
 454                  * We're mapping a single page, and the desired
 455                  * page protection is consistent with the bo.
 456                  */
 457
 458                 map->bo_kmap_type = ttm_bo_map_kmap;
 459                 map->page = ttm->pages[start_page];
 460                 map->virtual = kmap(map->page);
 461         } else {
 462                 /*
 463                  * We need to use vmap to get the desired page protection
 464                  * or to make the buffer object look contiguous.
 465                  */
 466                 prot = ttm_io_prot(mem->placement, PAGE_KERNEL);
 467                 map->bo_kmap_type = ttm_bo_map_vmap;
 468                 map->virtual = vmap(ttm->pages + start_page, num_pages,
 469                                     0, prot);
 470         }
 471         return (!map->virtual) ? -ENOMEM : 0;
 472 }
 473
 474 int ttm_bo_kmap(struct ttm_buffer_object *bo,
 475                 unsigned long start_page, unsigned long num_pages,
 476                 struct ttm_bo_kmap_obj *map)
 477 {
 478         unsigned long offset, size;
 479         int ret;
 480
 481         map->virtual = NULL;
 482         map->bo = bo;
 483         if (num_pages > bo->num_pages)
 484                 return -EINVAL;
 485         if (start_page > bo->num_pages)
 486                 return -EINVAL;
 487
 488         ret = ttm_mem_io_reserve(bo->bdev, &bo->mem);
 489         if (ret)
 490                 return ret;
 491         if (!bo->mem.bus.is_iomem) {
 492                 return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
 493         } else {
 494                 offset = start_page << PAGE_SHIFT;
 495                 size = num_pages << PAGE_SHIFT;
 496                 return ttm_bo_ioremap(bo, offset, size, map);
 497         }
 498 }
 499 EXPORT_SYMBOL(ttm_bo_kmap);
 500
 501 void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
 502 {
 503         if (!map->virtual)
 504                 return;
 505         switch (map->bo_kmap_type) {
 506         case ttm_bo_map_iomap:
 507                 iounmap(map->virtual);
 508                 break;
 509         case ttm_bo_map_vmap:
 510                 vunmap(map->virtual);
 511                 break;
 512         case ttm_bo_map_kmap:
 513                 kunmap(map->page);
 514                 break;
 515         case ttm_bo_map_premapped:
 516                 break;
 517         default:
 518                 BUG();
 519         }
 520         ttm_mem_io_free(map->bo->bdev, &map->bo->mem);
 521         map->virtual = NULL;
 522         map->page = NULL;
 523 }
 524 EXPORT_SYMBOL(ttm_bo_kunmap);
 525
 526 int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
 527                               struct dma_fence *fence,
 528                               bool evict,
 529                               struct ttm_resource *new_mem)
 530 {
 531         struct ttm_bo_device *bdev = bo->bdev;
 532         struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
 533         struct ttm_resource *old_mem = &bo->mem;
 534         int ret;
 535         struct ttm_buffer_object *ghost_obj;
 536
 537         dma_resv_add_excl_fence(bo->base.resv, fence);
 538         if (evict) {
 539                 ret = ttm_bo_wait(bo, false, false);
 540                 if (ret)
 541                         return ret;
 542
 543                 if (!man->use_tt)
 544                         ttm_bo_tt_destroy(bo);
 545                 ttm_bo_free_old_node(bo);
 546         } else {
 547                 /**
 548                  * This should help pipeline ordinary buffer moves.
 549                  *
 550                  * Hang old buffer memory on a new buffer object,
 551                  * and leave it to be released when the GPU
 552                  * operation has completed.
 553                  */
 554
 555                 dma_fence_put(bo->moving);
 556                 bo->moving = dma_fence_get(fence);
 557
 558                 ret = ttm_buffer_object_transfer(bo, &ghost_obj);
 559                 if (ret)
 560                         return ret;
 561
 562                 dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
 563
 564                 /**
 565                  * If we're not moving to fixed memory, the TTM object
 566                  * needs to stay alive. Otherwhise hang it on the ghost
 567                  * bo to be unbound and destroyed.
 568                  */
 569
 570                 if (man->use_tt)
 571                         ghost_obj->ttm = NULL;
 572                 else
 573                         bo->ttm = NULL;
 574
 575                 dma_resv_unlock(&ghost_obj->base._resv);
 576                 ttm_bo_put(ghost_obj);
 577         }
 578
 579         *old_mem = *new_mem;
 580         new_mem->mm_node = NULL;
 581
 582         return 0;
 583 }
 584 EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
 585
 586 int ttm_bo_pipeline_move(struct ttm_buffer_object *bo,
 587                          struct dma_fence *fence, bool evict,
 588                          struct ttm_resource *new_mem)
 589 {
 590         struct ttm_bo_device *bdev = bo->bdev;
 591         struct ttm_resource *old_mem = &bo->mem;
 592
 593         struct ttm_resource_manager *from = ttm_manager_type(bdev, old_mem->mem_type);
 594         struct ttm_resource_manager *to = ttm_manager_type(bdev, new_mem->mem_type);
 595
 596         int ret;
 597
 598         dma_resv_add_excl_fence(bo->base.resv, fence);
 599
 600         if (!evict) {
 601                 struct ttm_buffer_object *ghost_obj;
 602
 603                 /**
 604                  * This should help pipeline ordinary buffer moves.
 605                  *
 606                  * Hang old buffer memory on a new buffer object,
 607                  * and leave it to be released when the GPU
 608                  * operation has completed.
 609                  */
 610
 611                 dma_fence_put(bo->moving);
 612                 bo->moving = dma_fence_get(fence);
 613
 614                 ret = ttm_buffer_object_transfer(bo, &ghost_obj);
 615                 if (ret)
 616                         return ret;
 617
 618                 dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
 619
 620                 /**
 621                  * If we're not moving to fixed memory, the TTM object
 622                  * needs to stay alive. Otherwhise hang it on the ghost
 623                  * bo to be unbound and destroyed.
 624                  */
 625
 626                 if (to->use_tt)
 627                         ghost_obj->ttm = NULL;
 628                 else
 629                         bo->ttm = NULL;
 630
 631                 dma_resv_unlock(&ghost_obj->base._resv);
 632                 ttm_bo_put(ghost_obj);
 633
 634         } else if (!from->use_tt) {
 635
 636                 /**
 637                  * BO doesn't have a TTM we need to bind/unbind. Just remember
 638                  * this eviction and free up the allocation
 639                  */
 640
 641                 spin_lock(&from->move_lock);
 642                 if (!from->move || dma_fence_is_later(fence, from->move)) {
 643                         dma_fence_put(from->move);
 644                         from->move = dma_fence_get(fence);
 645                 }
 646                 spin_unlock(&from->move_lock);
 647
 648                 ttm_bo_free_old_node(bo);
 649
 650                 dma_fence_put(bo->moving);
 651                 bo->moving = dma_fence_get(fence);
 652
 653         } else {
 654                 /**
 655                  * Last resort, wait for the move to be completed.
 656                  *
 657                  * Should never happen in pratice.
 658                  */
 659
 660                 ret = ttm_bo_wait(bo, false, false);
 661                 if (ret)
 662                         return ret;
 663
 664                 if (!to->use_tt)
 665                         ttm_bo_tt_destroy(bo);
 666                 ttm_bo_free_old_node(bo);
 667         }
 668
 669         *old_mem = *new_mem;
 670         new_mem->mm_node = NULL;
 671
 672         return 0;
 673 }
 674 EXPORT_SYMBOL(ttm_bo_pipeline_move);
 675
 676 int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 677 {
 678         struct ttm_buffer_object *ghost;
 679         int ret;
 680
 681         ret = ttm_buffer_object_transfer(bo, &ghost);
 682         if (ret)
 683                 return ret;
 684
 685         ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
 686         /* Last resort, wait for the BO to be idle when we are OOM */
 687         if (ret)
 688                 ttm_bo_wait(bo, false, false);
 689
 690         memset(&bo->mem, 0, sizeof(bo->mem));
 691         bo->mem.mem_type = TTM_PL_SYSTEM;
 692         bo->ttm = NULL;
 693
 694         dma_resv_unlock(&ghost->base._resv);
 695         ttm_bo_put(ghost);
 696
 697         return 0;
 698 }
 699