src/gbm/main/gbm.c

   1 /*
   2  * Copyright © 2011 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  19  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  20  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22  * DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Benjamin Franzke <benjaminfranzke@googlemail.com>
  26  */
  27
  28 #include <stddef.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <stdint.h>
  33
  34 #ifdef MAJOR_IN_MKDEV
  35 #include <sys/mkdev.h>
  36 #endif
  37 #ifdef MAJOR_IN_SYSMACROS
  38 #include <sys/sysmacros.h>
  39 #endif
  40 #include <sys/stat.h>
  41 #include <unistd.h>
  42 #include <errno.h>
  43
  44 #include "gbm.h"
  45 #include "gbmint.h"
  46 #include "backend.h"
  47
  48 /** Returns the file description for the gbm device
  49  *
  50  * \return The fd that the struct gbm_device was created with
  51  */
  52 GBM_EXPORT int
  53 gbm_device_get_fd(struct gbm_device *gbm)
  54 {
  55    return gbm->fd;
  56 }
  57
  58 /** Get the backend name for the given gbm device
  59  *
  60  * \return The backend name string - this belongs to the device and must not
  61  * be freed
  62  */
  63 GBM_EXPORT const char *
  64 gbm_device_get_backend_name(struct gbm_device *gbm)
  65 {
  66    return gbm->name;
  67 }
  68
  69 /** Test if a format is supported for a given set of usage flags.
  70  *
  71  * \param gbm The created buffer manager
  72  * \param format The format to test
  73  * \param usage A bitmask of the usages to test the format against
  74  * \return 1 if the format is supported otherwise 0
  75  *
  76  * \sa enum gbm_bo_flags for the list of flags that the format can be
  77  * tested against
  78  *
  79  * \sa enum gbm_bo_format for the list of formats
  80  */
  81 GBM_EXPORT int
  82 gbm_device_is_format_supported(struct gbm_device *gbm,
  83                                uint32_t format, uint32_t usage)
  84 {
  85    return gbm->is_format_supported(gbm, format, usage);
  86 }
  87
  88 /** Get the number of planes that are required for a given format+modifier
  89  *
  90  * \param gbm The gbm device returned from gbm_create_device()
  91  * \param format The format to query
  92  * \param modifier The modifier to query
  93  */
  94 GBM_EXPORT int
  95 gbm_device_get_format_modifier_plane_count(struct gbm_device *gbm,
  96                                            uint32_t format,
  97                                            uint64_t modifier)
  98 {
  99    return gbm->get_format_modifier_plane_count(gbm, format, modifier);
 100 }
 101
 102 /** Destroy the gbm device and free all resources associated with it.
 103  *
 104  * \param gbm The device created using gbm_create_device()
 105  */
 106 GBM_EXPORT void
 107 gbm_device_destroy(struct gbm_device *gbm)
 108 {
 109    gbm->refcount--;
 110    if (gbm->refcount == 0)
 111       gbm->destroy(gbm);
 112 }
 113
 114 /** Create a gbm device for allocating buffers
 115  *
 116  * The file descriptor passed in is used by the backend to communicate with
 117  * platform for allocating the memory. For allocations using DRI this would be
 118  * the file descriptor returned when opening a device such as \c
 119  * /dev/dri/card0
 120  *
 121  * \param fd The file descriptor for a backend specific device
 122  * \return The newly created struct gbm_device. The resources associated with
 123  * the device should be freed with gbm_device_destroy() when it is no longer
 124  * needed. If the creation of the device failed NULL will be returned.
 125  */
 126 GBM_EXPORT struct gbm_device *
 127 gbm_create_device(int fd)
 128 {
 129    struct gbm_device *gbm = NULL;
 130    struct stat buf;
 131
 132    if (fd < 0 || fstat(fd, &buf) < 0 || !S_ISCHR(buf.st_mode)) {
 133       errno = EINVAL;
 134       return NULL;
 135    }
 136
 137    gbm = _gbm_create_device(fd);
 138    if (gbm == NULL)
 139       return NULL;
 140
 141    gbm->dummy = gbm_create_device;
 142    gbm->stat = buf;
 143    gbm->refcount = 1;
 144
 145    return gbm;
 146 }
 147
 148 /** Get the width of the buffer object
 149  *
 150  * \param bo The buffer object
 151  * \return The width of the allocated buffer object
 152  *
 153  */
 154 GBM_EXPORT uint32_t
 155 gbm_bo_get_width(struct gbm_bo *bo)
 156 {
 157    return bo->width;
 158 }
 159
 160 /** Get the height of the buffer object
 161  *
 162  * \param bo The buffer object
 163  * \return The height of the allocated buffer object
 164  */
 165 GBM_EXPORT uint32_t
 166 gbm_bo_get_height(struct gbm_bo *bo)
 167 {
 168    return bo->height;
 169 }
 170
 171 /** Get the stride of the buffer object
 172  *
 173  * This is calculated by the backend when it does the allocation in
 174  * gbm_bo_create()
 175  *
 176  * \param bo The buffer object
 177  * \return The stride of the allocated buffer object in bytes
 178  */
 179 GBM_EXPORT uint32_t
 180 gbm_bo_get_stride(struct gbm_bo *bo)
 181 {
 182    return gbm_bo_get_stride_for_plane(bo, 0);
 183 }
 184
 185 /** Get the stride for the given plane
 186  *
 187  * \param bo The buffer object
 188  * \param plane for which you want the stride
 189  *
 190  * \sa gbm_bo_get_stride()
 191  */
 192 GBM_EXPORT uint32_t
 193 gbm_bo_get_stride_for_plane(struct gbm_bo *bo, int plane)
 194 {
 195    return bo->gbm->bo_get_stride(bo, plane);
 196 }
 197
 198 /** Get the format of the buffer object
 199  *
 200  * The format of the pixels in the buffer.
 201  *
 202  * \param bo The buffer object
 203  * \return The format of buffer object, one of the GBM_FORMAT_* codes
 204  */
 205 GBM_EXPORT uint32_t
 206 gbm_bo_get_format(struct gbm_bo *bo)
 207 {
 208    return bo->format;
 209 }
 210
 211 /** Get the bit-per-pixel of the buffer object's format
 212  *
 213  * The bits-per-pixel of the buffer object's format.
 214  *
 215  * Note; The 'in-memory pixel' concept makes no sense for YUV formats
 216  * (pixels are the result of the combination of multiple memory sources:
 217  * Y, Cb & Cr; usually these are even in separate buffers), so YUV
 218  * formats are not supported by this function.
 219  *
 220  * \param bo The buffer object
 221  * \return The number of bits0per-pixel of the buffer object's format.
 222  */
 223 GBM_EXPORT uint32_t
 224 gbm_bo_get_bpp(struct gbm_bo *bo)
 225 {
 226    switch (bo->format) {
 227       default:
 228          return 0;
 229       case GBM_FORMAT_C8:
 230       case GBM_FORMAT_R8:
 231       case GBM_FORMAT_RGB332:
 232       case GBM_FORMAT_BGR233:
 233          return 8;
 234       case GBM_FORMAT_GR88:
 235       case GBM_FORMAT_XRGB4444:
 236       case GBM_FORMAT_XBGR4444:
 237       case GBM_FORMAT_RGBX4444:
 238       case GBM_FORMAT_BGRX4444:
 239       case GBM_FORMAT_ARGB4444:
 240       case GBM_FORMAT_ABGR4444:
 241       case GBM_FORMAT_RGBA4444:
 242       case GBM_FORMAT_BGRA4444:
 243       case GBM_FORMAT_XRGB1555:
 244       case GBM_FORMAT_XBGR1555:
 245       case GBM_FORMAT_RGBX5551:
 246       case GBM_FORMAT_BGRX5551:
 247       case GBM_FORMAT_ARGB1555:
 248       case GBM_FORMAT_ABGR1555:
 249       case GBM_FORMAT_RGBA5551:
 250       case GBM_FORMAT_BGRA5551:
 251       case GBM_FORMAT_RGB565:
 252       case GBM_FORMAT_BGR565:
 253          return 16;
 254       case GBM_FORMAT_RGB888:
 255       case GBM_FORMAT_BGR888:
 256          return 24;
 257       case GBM_FORMAT_XRGB8888:
 258       case GBM_FORMAT_XBGR8888:
 259       case GBM_FORMAT_RGBX8888:
 260       case GBM_FORMAT_BGRX8888:
 261       case GBM_FORMAT_ARGB8888:
 262       case GBM_FORMAT_ABGR8888:
 263       case GBM_FORMAT_RGBA8888:
 264       case GBM_FORMAT_BGRA8888:
 265       case GBM_FORMAT_XRGB2101010:
 266       case GBM_FORMAT_XBGR2101010:
 267       case GBM_FORMAT_RGBX1010102:
 268       case GBM_FORMAT_BGRX1010102:
 269       case GBM_FORMAT_ARGB2101010:
 270       case GBM_FORMAT_ABGR2101010:
 271       case GBM_FORMAT_RGBA1010102:
 272       case GBM_FORMAT_BGRA1010102:
 273          return 32;
 274       case GBM_FORMAT_XBGR16161616F:
 275       case GBM_FORMAT_ABGR16161616F:
 276          return 64;
 277    }
 278 }
 279
 280 /** Get the offset for the data of the specified plane
 281  *
 282  * Extra planes, and even the first plane, may have an offset from the start of
 283  * the buffer object. This function will provide the offset for the given plane
 284  * to be used in various KMS APIs.
 285  *
 286  * \param bo The buffer object
 287  * \return The offset
 288  */
 289 GBM_EXPORT uint32_t
 290 gbm_bo_get_offset(struct gbm_bo *bo, int plane)
 291 {
 292    return bo->gbm->bo_get_offset(bo, plane);
 293 }
 294
 295 /** Get the gbm device used to create the buffer object
 296  *
 297  * \param bo The buffer object
 298  * \return Returns the gbm device with which the buffer object was created
 299  */
 300 GBM_EXPORT struct gbm_device *
 301 gbm_bo_get_device(struct gbm_bo *bo)
 302 {
 303         return bo->gbm;
 304 }
 305
 306 /** Get the handle of the buffer object
 307  *
 308  * This is stored in the platform generic union gbm_bo_handle type. However
 309  * the format of this handle is platform specific.
 310  *
 311  * \param bo The buffer object
 312  * \return Returns the handle of the allocated buffer object
 313  */
 314 GBM_EXPORT union gbm_bo_handle
 315 gbm_bo_get_handle(struct gbm_bo *bo)
 316 {
 317    return bo->handle;
 318 }
 319
 320 /** Get a DMA-BUF file descriptor for the buffer object
 321  *
 322  * This function creates a DMA-BUF (also known as PRIME) file descriptor
 323  * handle for the buffer object.  Each call to gbm_bo_get_fd() returns a new
 324  * file descriptor and the caller is responsible for closing the file
 325  * descriptor.
 326
 327  * \param bo The buffer object
 328  * \return Returns a file descriptor referring to the underlying buffer or -1
 329  * if an error occurs.
 330  */
 331 GBM_EXPORT int
 332 gbm_bo_get_fd(struct gbm_bo *bo)
 333 {
 334    return bo->gbm->bo_get_fd(bo);
 335 }
 336
 337 /** Get the number of planes for the given bo.
 338  *
 339  * \param bo The buffer object
 340  * \return The number of planes
 341  */
 342 GBM_EXPORT int
 343 gbm_bo_get_plane_count(struct gbm_bo *bo)
 344 {
 345    return bo->gbm->bo_get_planes(bo);
 346 }
 347
 348 /** Get the handle for the specified plane of the buffer object
 349  *
 350  * This function gets the handle for any plane associated with the BO. When
 351  * dealing with multi-planar formats, or formats which might have implicit
 352  * planes based on different underlying hardware it is necessary for the client
 353  * to be able to get this information to pass to the DRM.
 354  *
 355  * \param bo The buffer object
 356  * \param plane the plane to get a handle for
 357  *
 358  * \sa gbm_bo_get_handle()
 359  */
 360 GBM_EXPORT union gbm_bo_handle
 361 gbm_bo_get_handle_for_plane(struct gbm_bo *bo, int plane)
 362 {
 363    return bo->gbm->bo_get_handle(bo, plane);
 364 }
 365
 366 /**
 367  * Get the chosen modifier for the buffer object
 368  *
 369  * This function returns the modifier that was chosen for the object. These
 370  * properties may be generic, or platform/implementation dependent.
 371  *
 372  * \param bo The buffer object
 373  * \return Returns the selected modifier (chosen by the implementation) for the
 374  * BO.
 375  * \sa gbm_bo_create_with_modifiers() where possible modifiers are set
 376  * \sa gbm_surface_create_with_modifiers() where possible modifiers are set
 377  * \sa define DRM_FORMAT_MOD_* in drm_fourcc.h for possible modifiers
 378  */
 379 GBM_EXPORT uint64_t
 380 gbm_bo_get_modifier(struct gbm_bo *bo)
 381 {
 382    return bo->gbm->bo_get_modifier(bo);
 383 }
 384
 385 /** Write data into the buffer object
 386  *
 387  * If the buffer object was created with the GBM_BO_USE_WRITE flag,
 388  * this function can be used to write data into the buffer object.  The
 389  * data is copied directly into the object and it's the responsibility
 390  * of the caller to make sure the data represents valid pixel data,
 391  * according to the width, height, stride and format of the buffer object.
 392  *
 393  * \param bo The buffer object
 394  * \param buf The data to write
 395  * \param count The number of bytes to write
 396  * \return Returns 0 on success, otherwise -1 is returned an errno set
 397  */
 398 GBM_EXPORT int
 399 gbm_bo_write(struct gbm_bo *bo, const void *buf, size_t count)
 400 {
 401    return bo->gbm->bo_write(bo, buf, count);
 402 }
 403
 404 /** Set the user data associated with a buffer object
 405  *
 406  * \param bo The buffer object
 407  * \param data The data to associate to the buffer object
 408  * \param destroy_user_data A callback (which may be %NULL) that will be
 409  * called prior to the buffer destruction
 410  */
 411 GBM_EXPORT void
 412 gbm_bo_set_user_data(struct gbm_bo *bo, void *data,
 413                      void (*destroy_user_data)(struct gbm_bo *, void *))
 414 {
 415    bo->user_data = data;
 416    bo->destroy_user_data = destroy_user_data;
 417 }
 418
 419 /** Get the user data associated with a buffer object
 420  *
 421  * \param bo The buffer object
 422  * \return Returns the user data associated with the buffer object or %NULL
 423  * if no data was associated with it
 424  *
 425  * \sa gbm_bo_set_user_data()
 426  */
 427 GBM_EXPORT void *
 428 gbm_bo_get_user_data(struct gbm_bo *bo)
 429 {
 430    return bo->user_data;
 431 }
 432
 433 /**
 434  * Destroys the given buffer object and frees all resources associated with
 435  * it.
 436  *
 437  * \param bo The buffer object
 438  */
 439 GBM_EXPORT void
 440 gbm_bo_destroy(struct gbm_bo *bo)
 441 {
 442    if (bo->destroy_user_data)
 443       bo->destroy_user_data(bo, bo->user_data);
 444
 445    bo->gbm->bo_destroy(bo);
 446 }
 447
 448 /**
 449  * Allocate a buffer object for the given dimensions
 450  *
 451  * \param gbm The gbm device returned from gbm_create_device()
 452  * \param width The width for the buffer
 453  * \param height The height for the buffer
 454  * \param format The format to use for the buffer, from GBM_FORMAT_* or
 455  * GBM_BO_FORMAT_* tokens
 456  * \param usage The union of the usage flags for this buffer
 457  *
 458  * \return A newly allocated buffer that should be freed with gbm_bo_destroy()
 459  * when no longer needed. If an error occurs during allocation %NULL will be
 460  * returned and errno set.
 461  *
 462  * \sa enum gbm_bo_flags for the list of usage flags
 463  */
 464 GBM_EXPORT struct gbm_bo *
 465 gbm_bo_create(struct gbm_device *gbm,
 466               uint32_t width, uint32_t height,
 467               uint32_t format, uint32_t usage)
 468 {
 469    if (width == 0 || height == 0) {
 470       errno = EINVAL;
 471       return NULL;
 472    }
 473
 474    return gbm->bo_create(gbm, width, height, format, usage, NULL, 0);
 475 }
 476
 477 GBM_EXPORT struct gbm_bo *
 478 gbm_bo_create_with_modifiers(struct gbm_device *gbm,
 479                              uint32_t width, uint32_t height,
 480                              uint32_t format,
 481                              const uint64_t *modifiers,
 482                              const unsigned int count)
 483 {
 484    if (width == 0 || height == 0) {
 485       errno = EINVAL;
 486       return NULL;
 487    }
 488
 489    if ((count && !modifiers) || (modifiers && !count)) {
 490       errno = EINVAL;
 491       return NULL;
 492    }
 493
 494    return gbm->bo_create(gbm, width, height, format, 0, modifiers, count);
 495 }
 496
 497 /**
 498  * Create a gbm buffer object from a foreign object
 499  *
 500  * This function imports a foreign object and creates a new gbm bo for it.
 501  * This enables using the foreign object with a display API such as KMS.
 502  * Currently these types of foreign objects are supported, indicated by the type
 503  * argument:
 504  *
 505  *   GBM_BO_IMPORT_WL_BUFFER
 506  *   GBM_BO_IMPORT_EGL_IMAGE
 507  *   GBM_BO_IMPORT_FD
 508  *   GBM_BO_IMPORT_FD_MODIFIER
 509  *
 510  * The gbm bo shares the underlying pixels but its life-time is
 511  * independent of the foreign object.
 512  *
 513  * \param gbm The gbm device returned from gbm_create_device()
 514  * \param type The type of object we're importing
 515  * \param buffer Pointer to the external object
 516  * \param usage The union of the usage flags for this buffer
 517  *
 518  * \return A newly allocated buffer object that should be freed with
 519  * gbm_bo_destroy() when no longer needed. On error, %NULL is returned
 520  * and errno is set.
 521  *
 522  * \sa enum gbm_bo_flags for the list of usage flags
 523  */
 524 GBM_EXPORT struct gbm_bo *
 525 gbm_bo_import(struct gbm_device *gbm,
 526               uint32_t type, void *buffer, uint32_t usage)
 527 {
 528    return gbm->bo_import(gbm, type, buffer, usage);
 529 }
 530
 531 /**
 532  * Map a region of a gbm buffer object for cpu access
 533  *
 534  * This function maps a region of a gbm bo for cpu read and/or write
 535  * access.
 536  *
 537  * The mapping exposes a linear view of the buffer object even if the buffer
 538  * has a non-linear modifier.
 539  *
 540  * This function may require intermediate buffer copies (ie. it may be slow).
 541  *
 542  * \param bo The buffer object
 543  * \param x The X (top left origin) starting position of the mapped region for
 544  * the buffer
 545  * \param y The Y (top left origin) starting position of the mapped region for
 546  * the buffer
 547  * \param width The width of the mapped region for the buffer
 548  * \param height The height of the mapped region for the buffer
 549  * \param flags The union of the GBM_BO_TRANSFER_* flags for this buffer
 550  * \param stride Ptr for returned stride in bytes of the mapped region
 551  * \param map_data Returned opaque ptr for the mapped region
 552  *
 553  * \return Address of the mapped buffer that should be unmapped with
 554  * gbm_bo_unmap() when no longer needed. On error, %NULL is returned
 555  * and errno is set.
 556  *
 557  * \sa enum gbm_bo_transfer_flags for the list of flags
 558  */
 559 GBM_EXPORT void *
 560 gbm_bo_map(struct gbm_bo *bo,
 561               uint32_t x, uint32_t y,
 562               uint32_t width, uint32_t height,
 563               uint32_t flags, uint32_t *stride, void **map_data)
 564 {
 565    if (!bo || width == 0 || height == 0 || !stride || !map_data) {
 566       errno = EINVAL;
 567       return NULL;
 568    }
 569
 570    return bo->gbm->bo_map(bo, x, y, width, height,
 571                           flags, stride, map_data);
 572 }
 573
 574 /**
 575  * Unmap a previously mapped region of a gbm buffer object
 576  *
 577  * This function unmaps a region of a gbm bo for cpu read and/or write
 578  * access.
 579  *
 580  * \param bo The buffer object
 581  * \param map_data opaque ptr returned from prior gbm_bo_map
 582  */
 583 GBM_EXPORT void
 584 gbm_bo_unmap(struct gbm_bo *bo, void *map_data)
 585 {
 586    bo->gbm->bo_unmap(bo, map_data);
 587 }
 588
 589 /**
 590  * Allocate a surface object
 591  *
 592  * \param gbm The gbm device returned from gbm_create_device()
 593  * \param width The width for the surface
 594  * \param height The height for the surface
 595  * \param format The format to use for the surface
 596  *
 597  * \return A newly allocated surface that should be freed with
 598  * gbm_surface_destroy() when no longer needed. If an error occurs
 599  * during allocation %NULL will be returned.
 600  *
 601  * \sa enum gbm_bo_format for the list of formats
 602  */
 603 GBM_EXPORT struct gbm_surface *
 604 gbm_surface_create(struct gbm_device *gbm,
 605                    uint32_t width, uint32_t height,
 606                    uint32_t format, uint32_t flags)
 607 {
 608    return gbm->surface_create(gbm, width, height, format, flags, NULL, 0);
 609 }
 610
 611 GBM_EXPORT struct gbm_surface *
 612 gbm_surface_create_with_modifiers(struct gbm_device *gbm,
 613                                   uint32_t width, uint32_t height,
 614                                   uint32_t format,
 615                                   const uint64_t *modifiers,
 616                                   const unsigned int count)
 617 {
 618    if ((count && !modifiers) || (modifiers && !count)) {
 619       errno = EINVAL;
 620       return NULL;
 621    }
 622
 623    return gbm->surface_create(gbm, width, height, format, 0,
 624                               modifiers, count);
 625 }
 626
 627 /**
 628  * Destroys the given surface and frees all resources associated with
 629  * it.
 630  *
 631  * All buffers locked with gbm_surface_lock_front_buffer() should be
 632  * released prior to calling this function.
 633  *
 634  * \param surf The surface
 635  */
 636 GBM_EXPORT void
 637 gbm_surface_destroy(struct gbm_surface *surf)
 638 {
 639    surf->gbm->surface_destroy(surf);
 640 }
 641
 642 /**
 643  * Lock the surface's current front buffer
 644  *
 645  * Lock rendering to the surface's current front buffer until it is
 646  * released with gbm_surface_release_buffer().
 647  *
 648  * This function must be called exactly once after calling
 649  * eglSwapBuffers.  Calling it before any eglSwapBuffer has happened
 650  * on the surface or two or more times after eglSwapBuffers is an
 651  * error.  A new bo representing the new front buffer is returned.  On
 652  * multiple invocations, all the returned bos must be released in
 653  * order to release the actual surface buffer.
 654  *
 655  * \param surf The surface
 656  *
 657  * \return A buffer object that should be released with
 658  * gbm_surface_release_buffer() when no longer needed.  The implementation
 659  * is free to reuse buffers released with gbm_surface_release_buffer() so
 660  * this bo should not be destroyed using gbm_bo_destroy().  If an error
 661  * occurs this function returns %NULL.
 662  */
 663 GBM_EXPORT struct gbm_bo *
 664 gbm_surface_lock_front_buffer(struct gbm_surface *surf)
 665 {
 666    return surf->gbm->surface_lock_front_buffer(surf);
 667 }
 668
 669 /**
 670  * Release a locked buffer obtained with gbm_surface_lock_front_buffer()
 671  *
 672  * Returns the underlying buffer to the gbm surface.  Releasing a bo
 673  * will typically make gbm_surface_has_free_buffer() return 1 and thus
 674  * allow rendering the next frame, but not always. The implementation
 675  * may choose to destroy the bo immediately or reuse it, in which case
 676  * the user data associated with it is unchanged.
 677  *
 678  * \param surf The surface
 679  * \param bo The buffer object
 680  */
 681 GBM_EXPORT void
 682 gbm_surface_release_buffer(struct gbm_surface *surf, struct gbm_bo *bo)
 683 {
 684    surf->gbm->surface_release_buffer(surf, bo);
 685 }
 686
 687 /**
 688  * Return whether or not a surface has free (non-locked) buffers
 689  *
 690  * Before starting a new frame, the surface must have a buffer
 691  * available for rendering.  Initially, a gbm surface will have a free
 692  * buffer, but after one or more buffers have been locked (\sa
 693  * gbm_surface_lock_front_buffer()), the application must check for a
 694  * free buffer before rendering.
 695  *
 696  * If a surface doesn't have a free buffer, the application must
 697  * return a buffer to the surface using gbm_surface_release_buffer()
 698  * and after that, the application can query for free buffers again.
 699  *
 700  * \param surf The surface
 701  * \return 1 if the surface has free buffers, 0 otherwise
 702  */
 703 GBM_EXPORT int
 704 gbm_surface_has_free_buffers(struct gbm_surface *surf)
 705 {
 706    return surf->gbm->surface_has_free_buffers(surf);
 707 }
 708
 709 /* The two GBM_BO_FORMAT_[XA]RGB8888 formats alias the GBM_FORMAT_*
 710  * formats of the same name. We want to accept them whenever someone
 711  * has a GBM format, but never return them to the user. */
 712 uint32_t
 713 gbm_format_canonicalize(uint32_t gbm_format)
 714 {
 715    switch (gbm_format) {
 716    case GBM_BO_FORMAT_XRGB8888:
 717       return GBM_FORMAT_XRGB8888;
 718    case GBM_BO_FORMAT_ARGB8888:
 719       return GBM_FORMAT_ARGB8888;
 720    default:
 721       return gbm_format;
 722    }
 723 }
 724
 725 /**
 726  * Returns a string representing the fourcc format name.
 727  *
 728  * \param desc Caller-provided storage for the format name string.
 729  * \return String containing the fourcc of the format.
 730  */
 731 GBM_EXPORT char *
 732 gbm_format_get_name(uint32_t gbm_format, struct gbm_format_name_desc *desc)
 733 {
 734    gbm_format = gbm_format_canonicalize(gbm_format);
 735
 736    desc->name[0] = gbm_format;
 737    desc->name[1] = gbm_format >> 8;
 738    desc->name[2] = gbm_format >> 16;
 739    desc->name[3] = gbm_format >> 24;
 740    desc->name[4] = 0;
 741
 742    return desc->name;
 743 }