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_bo_tt_unbind(bo);
  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
  81                 ret = ttm_tt_populate(bo->bdev, ttm, ctx);
  82                 if (unlikely(ret != 0))
  83                         return ret;
  84
  85                 ret = ttm_bo_tt_bind(bo, new_mem);
  86                 if (unlikely(ret != 0))
  87                         return ret;
  88         }
  89
  90         ttm_bo_assign_mem(bo, new_mem);
  91         return 0;
  92 }
  93 EXPORT_SYMBOL(ttm_bo_move_ttm);
  94
  95 int ttm_mem_io_reserve(struct ttm_bo_device *bdev,
  96                        struct ttm_resource *mem)
  97 {
  98         if (mem->bus.offset || mem->bus.addr)
  99                 return 0;
 100
 101         mem->bus.is_iomem = false;
 102         if (!bdev->driver->io_mem_reserve)
 103                 return 0;
 104
 105         return bdev->driver->io_mem_reserve(bdev, mem);
 106 }
 107
 108 void ttm_mem_io_free(struct ttm_bo_device *bdev,
 109                      struct ttm_resource *mem)
 110 {
 111         if (!mem->bus.offset && !mem->bus.addr)
 112                 return;
 113
 114         if (bdev->driver->io_mem_free)
 115                 bdev->driver->io_mem_free(bdev, mem);
 116
 117         mem->bus.offset = 0;
 118         mem->bus.addr = NULL;
 119 }
 120
 121 static int ttm_resource_ioremap(struct ttm_bo_device *bdev,
 122                                struct ttm_resource *mem,
 123                                void **virtual)
 124 {
 125         int ret;
 126         void *addr;
 127
 128         *virtual = NULL;
 129         ret = ttm_mem_io_reserve(bdev, mem);
 130         if (ret || !mem->bus.is_iomem)
 131                 return ret;
 132
 133         if (mem->bus.addr) {
 134                 addr = mem->bus.addr;
 135         } else {
 136                 size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
 137
 138                 if (mem->placement & TTM_PL_FLAG_WC)
 139                         addr = ioremap_wc(mem->bus.offset, bus_size);
 140                 else
 141                         addr = ioremap(mem->bus.offset, bus_size);
 142                 if (!addr) {
 143                         ttm_mem_io_free(bdev, mem);
 144                         return -ENOMEM;
 145                 }
 146         }
 147         *virtual = addr;
 148         return 0;
 149 }
 150
 151 static void ttm_resource_iounmap(struct ttm_bo_device *bdev,
 152                                 struct ttm_resource *mem,
 153                                 void *virtual)
 154 {
 155         if (virtual && mem->bus.addr == NULL)
 156                 iounmap(virtual);
 157         ttm_mem_io_free(bdev, mem);
 158 }
 159
 160 static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
 161 {
 162         uint32_t *dstP =
 163             (uint32_t *) ((unsigned long)dst + (page << PAGE_SHIFT));
 164         uint32_t *srcP =
 165             (uint32_t *) ((unsigned long)src + (page << PAGE_SHIFT));
 166
 167         int i;
 168         for (i = 0; i < PAGE_SIZE / sizeof(uint32_t); ++i)
 169                 iowrite32(ioread32(srcP++), dstP++);
 170         return 0;
 171 }
 172
 173 static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
 174                                 unsigned long page,
 175                                 pgprot_t prot)
 176 {
 177         struct page *d = ttm->pages[page];
 178         void *dst;
 179
 180         if (!d)
 181                 return -ENOMEM;
 182
 183         src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
 184         dst = kmap_atomic_prot(d, prot);
 185         if (!dst)
 186                 return -ENOMEM;
 187
 188         memcpy_fromio(dst, src, PAGE_SIZE);
 189
 190         kunmap_atomic(dst);
 191
 192         return 0;
 193 }
 194
 195 static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
 196                                 unsigned long page,
 197                                 pgprot_t prot)
 198 {
 199         struct page *s = ttm->pages[page];
 200         void *src;
 201
 202         if (!s)
 203                 return -ENOMEM;
 204
 205         dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
 206         src = kmap_atomic_prot(s, prot);
 207         if (!src)
 208                 return -ENOMEM;
 209
 210         memcpy_toio(dst, src, PAGE_SIZE);
 211
 212         kunmap_atomic(src);
 213
 214         return 0;
 215 }
 216
 217 int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 218                        struct ttm_operation_ctx *ctx,
 219                        struct ttm_resource *new_mem)
 220 {
 221         struct ttm_bo_device *bdev = bo->bdev;
 222         struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
 223         struct ttm_tt *ttm = bo->ttm;
 224         struct ttm_resource *old_mem = &bo->mem;
 225         struct ttm_resource old_copy = *old_mem;
 226         void *old_iomap;
 227         void *new_iomap;
 228         int ret;
 229         unsigned long i;
 230         unsigned long page;
 231         unsigned long add = 0;
 232         int dir;
 233
 234         ret = ttm_bo_wait(bo, ctx->interruptible, ctx->no_wait_gpu);
 235         if (ret)
 236                 return ret;
 237
 238         ret = ttm_resource_ioremap(bdev, old_mem, &old_iomap);
 239         if (ret)
 240                 return ret;
 241         ret = ttm_resource_ioremap(bdev, new_mem, &new_iomap);
 242         if (ret)
 243                 goto out;
 244
 245         /*
 246          * Single TTM move. NOP.
 247          */
 248         if (old_iomap == NULL && new_iomap == NULL)
 249                 goto out2;
 250
 251         /*
 252          * Don't move nonexistent data. Clear destination instead.
 253          */
 254         if (old_iomap == NULL &&
 255             (ttm == NULL || (!ttm_tt_is_populated(ttm) &&
 256                              !(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)))) {
 257                 memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
 258                 goto out2;
 259         }
 260
 261         /*
 262          * TTM might be null for moves within the same region.
 263          */
 264         if (ttm) {
 265                 ret = ttm_tt_populate(bdev, ttm, ctx);
 266                 if (ret)
 267                         goto out1;
 268         }
 269
 270         add = 0;
 271         dir = 1;
 272
 273         if ((old_mem->mem_type == new_mem->mem_type) &&
 274             (new_mem->start < old_mem->start + old_mem->size)) {
 275                 dir = -1;
 276                 add = new_mem->num_pages - 1;
 277         }
 278
 279         for (i = 0; i < new_mem->num_pages; ++i) {
 280                 page = i * dir + add;
 281                 if (old_iomap == NULL) {
 282                         pgprot_t prot = ttm_io_prot(old_mem->placement,
 283                                                     PAGE_KERNEL);
 284                         ret = ttm_copy_ttm_io_page(ttm, new_iomap, page,
 285                                                    prot);
 286                 } else if (new_iomap == NULL) {
 287                         pgprot_t prot = ttm_io_prot(new_mem->placement,
 288                                                     PAGE_KERNEL);
 289                         ret = ttm_copy_io_ttm_page(ttm, old_iomap, page,
 290                                                    prot);
 291                 } else {
 292                         ret = ttm_copy_io_page(new_iomap, old_iomap, page);
 293                 }
 294                 if (ret)
 295                         goto out1;
 296         }
 297         mb();
 298 out2:
 299         old_copy = *old_mem;
 300
 301         ttm_bo_assign_mem(bo, new_mem);
 302
 303         if (!man->use_tt)
 304                 ttm_bo_tt_destroy(bo);
 305
 306 out1:
 307         ttm_resource_iounmap(bdev, old_mem, new_iomap);
 308 out:
 309         ttm_resource_iounmap(bdev, &old_copy, old_iomap);
 310
 311         /*
 312          * On error, keep the mm node!
 313          */
 314         if (!ret)
 315                 ttm_resource_free(bo, &old_copy);
 316         return ret;
 317 }
 318 EXPORT_SYMBOL(ttm_bo_move_memcpy);
 319
 320 static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
 321 {
 322         struct ttm_transfer_obj *fbo;
 323
 324         fbo = container_of(bo, struct ttm_transfer_obj, base);
 325         ttm_bo_put(fbo->bo);
 326         kfree(fbo);
 327 }
 328
 329 /**
 330  * ttm_buffer_object_transfer
 331  *
 332  * @bo: A pointer to a struct ttm_buffer_object.
 333  * @new_obj: A pointer to a pointer to a newly created ttm_buffer_object,
 334  * holding the data of @bo with the old placement.
 335  *
 336  * This is a utility function that may be called after an accelerated move
 337  * has been scheduled. A new buffer object is created as a placeholder for
 338  * the old data while it's being copied. When that buffer object is idle,
 339  * it can be destroyed, releasing the space of the old placement.
 340  * Returns:
 341  * !0: Failure.
 342  */
 343
 344 static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 345                                       struct ttm_buffer_object **new_obj)
 346 {
 347         struct ttm_transfer_obj *fbo;
 348         int ret;
 349
 350         fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
 351         if (!fbo)
 352                 return -ENOMEM;
 353
 354         fbo->base = *bo;
 355         fbo->base.mem.placement |= TTM_PL_FLAG_NO_EVICT;
 356
 357         ttm_bo_get(bo);
 358         fbo->bo = bo;
 359
 360         /**
 361          * Fix up members that we shouldn't copy directly:
 362          * TODO: Explicit member copy would probably be better here.
 363          */
 364
 365         atomic_inc(&ttm_bo_glob.bo_count);
 366         INIT_LIST_HEAD(&fbo->base.ddestroy);
 367         INIT_LIST_HEAD(&fbo->base.lru);
 368         INIT_LIST_HEAD(&fbo->base.swap);
 369         fbo->base.moving = NULL;
 370         drm_vma_node_reset(&fbo->base.base.vma_node);
 371
 372         kref_init(&fbo->base.kref);
 373         fbo->base.destroy = &ttm_transfered_destroy;
 374         fbo->base.acc_size = 0;
 375         if (bo->type != ttm_bo_type_sg)
 376                 fbo->base.base.resv = &fbo->base.base._resv;
 377
 378         dma_resv_init(&fbo->base.base._resv);
 379         fbo->base.base.dev = NULL;
 380         ret = dma_resv_trylock(&fbo->base.base._resv);
 381         WARN_ON(!ret);
 382
 383         *new_obj = &fbo->base;
 384         return 0;
 385 }
 386
 387 pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
 388 {
 389         /* Cached mappings need no adjustment */
 390         if (caching_flags & TTM_PL_FLAG_CACHED)
 391                 return tmp;
 392
 393 #if defined(__i386__) || defined(__x86_64__)
 394         if (caching_flags & TTM_PL_FLAG_WC)
 395                 tmp = pgprot_writecombine(tmp);
 396         else if (boot_cpu_data.x86 > 3)
 397                 tmp = pgprot_noncached(tmp);
 398 #endif
 399 #if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
 400     defined(__powerpc__) || defined(__mips__)
 401         if (caching_flags & TTM_PL_FLAG_WC)
 402                 tmp = pgprot_writecombine(tmp);
 403         else
 404                 tmp = pgprot_noncached(tmp);
 405 #endif
 406 #if defined(__sparc__)
 407         tmp = pgprot_noncached(tmp);
 408 #endif
 409         return tmp;
 410 }
 411 EXPORT_SYMBOL(ttm_io_prot);
 412
 413 static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
 414                           unsigned long offset,
 415                           unsigned long size,
 416                           struct ttm_bo_kmap_obj *map)
 417 {
 418         struct ttm_resource *mem = &bo->mem;
 419
 420         if (bo->mem.bus.addr) {
 421                 map->bo_kmap_type = ttm_bo_map_premapped;
 422                 map->virtual = (void *)(((u8 *)bo->mem.bus.addr) + offset);
 423         } else {
 424                 map->bo_kmap_type = ttm_bo_map_iomap;
 425                 if (mem->placement & TTM_PL_FLAG_WC)
 426                         map->virtual = ioremap_wc(bo->mem.bus.offset + offset,
 427                                                   size);
 428                 else
 429                         map->virtual = ioremap(bo->mem.bus.offset + offset,
 430                                                size);
 431         }
 432         return (!map->virtual) ? -ENOMEM : 0;
 433 }
 434
 435 static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
 436                            unsigned long start_page,
 437                            unsigned long num_pages,
 438                            struct ttm_bo_kmap_obj *map)
 439 {
 440         struct ttm_resource *mem = &bo->mem;
 441         struct ttm_operation_ctx ctx = {
 442                 .interruptible = false,
 443                 .no_wait_gpu = false
 444         };
 445         struct ttm_tt *ttm = bo->ttm;
 446         pgprot_t prot;
 447         int ret;
 448
 449         BUG_ON(!ttm);
 450
 451         ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
 452         if (ret)
 453                 return ret;
 454
 455         if (num_pages == 1 && (mem->placement & TTM_PL_FLAG_CACHED)) {
 456                 /*
 457                  * We're mapping a single page, and the desired
 458                  * page protection is consistent with the bo.
 459                  */
 460
 461                 map->bo_kmap_type = ttm_bo_map_kmap;
 462                 map->page = ttm->pages[start_page];
 463                 map->virtual = kmap(map->page);
 464         } else {
 465                 /*
 466                  * We need to use vmap to get the desired page protection
 467                  * or to make the buffer object look contiguous.
 468                  */
 469                 prot = ttm_io_prot(mem->placement, PAGE_KERNEL);
 470                 map->bo_kmap_type = ttm_bo_map_vmap;
 471                 map->virtual = vmap(ttm->pages + start_page, num_pages,
 472                                     0, prot);
 473         }
 474         return (!map->virtual) ? -ENOMEM : 0;
 475 }
 476
 477 int ttm_bo_kmap(struct ttm_buffer_object *bo,
 478                 unsigned long start_page, unsigned long num_pages,
 479                 struct ttm_bo_kmap_obj *map)
 480 {
 481         unsigned long offset, size;
 482         int ret;
 483
 484         map->virtual = NULL;
 485         map->bo = bo;
 486         if (num_pages > bo->num_pages)
 487                 return -EINVAL;
 488         if (start_page > bo->num_pages)
 489                 return -EINVAL;
 490
 491         ret = ttm_mem_io_reserve(bo->bdev, &bo->mem);
 492         if (ret)
 493                 return ret;
 494         if (!bo->mem.bus.is_iomem) {
 495                 return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
 496         } else {
 497                 offset = start_page << PAGE_SHIFT;
 498                 size = num_pages << PAGE_SHIFT;
 499                 return ttm_bo_ioremap(bo, offset, size, map);
 500         }
 501 }
 502 EXPORT_SYMBOL(ttm_bo_kmap);
 503
 504 void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
 505 {
 506         if (!map->virtual)
 507                 return;
 508         switch (map->bo_kmap_type) {
 509         case ttm_bo_map_iomap:
 510                 iounmap(map->virtual);
 511                 break;
 512         case ttm_bo_map_vmap:
 513                 vunmap(map->virtual);
 514                 break;
 515         case ttm_bo_map_kmap:
 516                 kunmap(map->page);
 517                 break;
 518         case ttm_bo_map_premapped:
 519                 break;
 520         default:
 521                 BUG();
 522         }
 523         ttm_mem_io_free(map->bo->bdev, &map->bo->mem);
 524         map->virtual = NULL;
 525         map->page = NULL;
 526 }
 527 EXPORT_SYMBOL(ttm_bo_kunmap);
 528
 529 static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
 530                                  bool dst_use_tt)
 531 {
 532         int ret;
 533         ret = ttm_bo_wait(bo, false, false);
 534         if (ret)
 535                 return ret;
 536
 537         if (!dst_use_tt)
 538                 ttm_bo_tt_destroy(bo);
 539         ttm_bo_free_old_node(bo);
 540         return 0;
 541 }
 542
 543 static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
 544                                 struct dma_fence *fence,
 545                                 bool dst_use_tt)
 546 {
 547         struct ttm_buffer_object *ghost_obj;
 548         int ret;
 549
 550         /**
 551          * This should help pipeline ordinary buffer moves.
 552          *
 553          * Hang old buffer memory on a new buffer object,
 554          * and leave it to be released when the GPU
 555          * operation has completed.
 556          */
 557
 558         dma_fence_put(bo->moving);
 559         bo->moving = dma_fence_get(fence);
 560
 561         ret = ttm_buffer_object_transfer(bo, &ghost_obj);
 562         if (ret)
 563                 return ret;
 564
 565         dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
 566
 567         /**
 568          * If we're not moving to fixed memory, the TTM object
 569          * needs to stay alive. Otherwhise hang it on the ghost
 570          * bo to be unbound and destroyed.
 571          */
 572
 573         if (dst_use_tt)
 574                 ghost_obj->ttm = NULL;
 575         else
 576                 bo->ttm = NULL;
 577
 578         dma_resv_unlock(&ghost_obj->base._resv);
 579         ttm_bo_put(ghost_obj);
 580         return 0;
 581 }
 582
 583 static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo,
 584                                        struct dma_fence *fence)
 585 {
 586         struct ttm_bo_device *bdev = bo->bdev;
 587         struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->mem.mem_type);
 588
 589         /**
 590          * BO doesn't have a TTM we need to bind/unbind. Just remember
 591          * this eviction and free up the allocation
 592          */
 593         spin_lock(&from->move_lock);
 594         if (!from->move || dma_fence_is_later(fence, from->move)) {
 595                 dma_fence_put(from->move);
 596                 from->move = dma_fence_get(fence);
 597         }
 598         spin_unlock(&from->move_lock);
 599
 600         ttm_bo_free_old_node(bo);
 601
 602         dma_fence_put(bo->moving);
 603         bo->moving = dma_fence_get(fence);
 604 }
 605
 606 int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
 607                               struct dma_fence *fence,
 608                               bool evict,
 609                               bool pipeline,
 610                               struct ttm_resource *new_mem)
 611 {
 612         struct ttm_bo_device *bdev = bo->bdev;
 613         struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->mem.mem_type);
 614         struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
 615         int ret = 0;
 616
 617         dma_resv_add_excl_fence(bo->base.resv, fence);
 618         if (!evict)
 619                 ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
 620         else if (!from->use_tt && pipeline)
 621                 ttm_bo_move_pipeline_evict(bo, fence);
 622         else
 623                 ret = ttm_bo_wait_free_node(bo, man->use_tt);
 624
 625         if (ret)
 626                 return ret;
 627
 628         ttm_bo_assign_mem(bo, new_mem);
 629
 630         return 0;
 631 }
 632 EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
 633
 634 int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 635 {
 636         struct ttm_buffer_object *ghost;
 637         int ret;
 638
 639         ret = ttm_buffer_object_transfer(bo, &ghost);
 640         if (ret)
 641                 return ret;
 642
 643         ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
 644         /* Last resort, wait for the BO to be idle when we are OOM */
 645         if (ret)
 646                 ttm_bo_wait(bo, false, false);
 647
 648         memset(&bo->mem, 0, sizeof(bo->mem));
 649         bo->mem.mem_type = TTM_PL_SYSTEM;
 650         bo->ttm = NULL;
 651
 652         dma_resv_unlock(&ghost->base._resv);
 653         ttm_bo_put(ghost);
 654
 655         return 0;
 656 }