path: root/src/vulkan/wsi/wsi_common.c

/*
 * Copyright © 2017 Intel Corporation
 *
 * 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.
 */

#include "wsi_common_private.h"
#include "util/macros.h"
#include "vk_util.h"

void
wsi_device_init(struct wsi_device *wsi,
                VkPhysicalDevice pdevice,
                WSI_FN_GetPhysicalDeviceProcAddr proc_addr)
{
   memset(wsi, 0, sizeof(*wsi));

#define WSI_GET_CB(func) \
   PFN_vk##func func = (PFN_vk##func)proc_addr(pdevice, "vk" #func)
   WSI_GET_CB(GetPhysicalDeviceMemoryProperties);
   WSI_GET_CB(GetPhysicalDeviceQueueFamilyProperties);
#undef WSI_GET_CB

   GetPhysicalDeviceMemoryProperties(pdevice, &wsi->memory_props);
   GetPhysicalDeviceQueueFamilyProperties(pdevice, &wsi->queue_family_count, NULL);

#define WSI_GET_CB(func) \
   wsi->func = (PFN_vk##func)proc_addr(pdevice, "vk" #func)
   WSI_GET_CB(AllocateMemory);
   WSI_GET_CB(AllocateCommandBuffers);
   WSI_GET_CB(BindBufferMemory);
   WSI_GET_CB(BindImageMemory);
   WSI_GET_CB(BeginCommandBuffer);
   WSI_GET_CB(CmdCopyImageToBuffer);
   WSI_GET_CB(CreateBuffer);
   WSI_GET_CB(CreateCommandPool);
   WSI_GET_CB(CreateFence);
   WSI_GET_CB(CreateImage);
   WSI_GET_CB(DestroyBuffer);
   WSI_GET_CB(DestroyCommandPool);
   WSI_GET_CB(DestroyFence);
   WSI_GET_CB(DestroyImage);
   WSI_GET_CB(EndCommandBuffer);
   WSI_GET_CB(FreeMemory);
   WSI_GET_CB(FreeCommandBuffers);
   WSI_GET_CB(GetBufferMemoryRequirements);
   WSI_GET_CB(GetImageMemoryRequirements);
   WSI_GET_CB(GetImageSubresourceLayout);
   WSI_GET_CB(GetMemoryFdKHR);
   WSI_GET_CB(ResetFences);
   WSI_GET_CB(QueueSubmit);
   WSI_GET_CB(WaitForFences);
#undef WSI_GET_CB
}

VkResult
wsi_swapchain_init(const struct wsi_device *wsi,
                   struct wsi_swapchain *chain,
                   VkDevice device,
                   const VkSwapchainCreateInfoKHR *pCreateInfo,
                   const VkAllocationCallbacks *pAllocator)
{
   VkResult result;

   memset(chain, 0, sizeof(*chain));

   chain->wsi = wsi;
   chain->device = device;
   chain->alloc = *pAllocator;

   chain->cmd_pools =
      vk_zalloc(pAllocator, sizeof(VkCommandPool) * wsi->queue_family_count, 8,
                VK_SYSTEM_ALLOCATION_SCOPE_OBJECT);
   if (!chain->cmd_pools)
      return VK_ERROR_OUT_OF_HOST_MEMORY;

   for (uint32_t i = 0; i < wsi->queue_family_count; i++) {
      const VkCommandPoolCreateInfo cmd_pool_info = {
         .sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO,
         .pNext = NULL,
         .flags = 0,
         .queueFamilyIndex = i,
      };
      result = wsi->CreateCommandPool(device, &cmd_pool_info, &chain->alloc,
                                      &chain->cmd_pools[i]);
      if (result != VK_SUCCESS)
         goto fail;
   }

   return VK_SUCCESS;

fail:
   wsi_swapchain_finish(chain);
   return result;
}

void
wsi_swapchain_finish(struct wsi_swapchain *chain)
{
   for (uint32_t i = 0; i < chain->wsi->queue_family_count; i++) {
      chain->wsi->DestroyCommandPool(chain->device, chain->cmd_pools[i],
                                     &chain->alloc);
   }
}

static uint32_t
select_memory_type(const struct wsi_device *wsi,
                   VkMemoryPropertyFlags props,
                   uint32_t type_bits)
{
   for (uint32_t i = 0; i < wsi->memory_props.memoryTypeCount; i++) {
       const VkMemoryType type = wsi->memory_props.memoryTypes[i];
       if ((type_bits & (1 << i)) && (type.propertyFlags & props) == props)
         return i;
   }

   unreachable("No memory type found");
}

static uint32_t
vk_format_size(VkFormat format)
{
   switch (format) {
   case VK_FORMAT_B8G8R8A8_UNORM:
   case VK_FORMAT_B8G8R8A8_SRGB:
      return 4;
   default:
      unreachable("Unknown WSI Format");
   }
}

static inline uint32_t
align_u32(uint32_t v, uint32_t a)
{
   assert(a != 0 && a == (a & -a));
   return (v + a - 1) & ~(a - 1);
}

VkResult
wsi_create_native_image(const struct wsi_swapchain *chain,
                        const VkSwapchainCreateInfoKHR *pCreateInfo,
                        struct wsi_image *image)
{
   const struct wsi_device *wsi = chain->wsi;
   VkResult result;

   memset(image, 0, sizeof(*image));

   const struct wsi_image_create_info image_wsi_info = {
      .sType = VK_STRUCTURE_TYPE_WSI_IMAGE_CREATE_INFO_MESA,
      .pNext = NULL,
      .scanout = true,
   };
   const VkImageCreateInfo image_info = {
      .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
      .pNext = &image_wsi_info,
      .flags = 0,
      .imageType = VK_IMAGE_TYPE_2D,
      .format = pCreateInfo->imageFormat,
      .extent = {
         .width = pCreateInfo->imageExtent.width,
         .height = pCreateInfo->imageExtent.height,
         .depth = 1,
      },
      .mipLevels = 1,
      .arrayLayers = 1,
      .samples = VK_SAMPLE_COUNT_1_BIT,
      .tiling = VK_IMAGE_TILING_OPTIMAL,
      .usage = pCreateInfo->imageUsage,
      .sharingMode = pCreateInfo->imageSharingMode,
      .queueFamilyIndexCount = pCreateInfo->queueFamilyIndexCount,
      .pQueueFamilyIndices = pCreateInfo->pQueueFamilyIndices,
      .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
   };
   result = wsi->CreateImage(chain->device, &image_info,
                             &chain->alloc, &image->image);
   if (result != VK_SUCCESS)
      goto fail;

   VkMemoryRequirements reqs;
   wsi->GetImageMemoryRequirements(chain->device, image->image, &reqs);

   VkSubresourceLayout image_layout;
   const VkImageSubresource image_subresource = {
      .aspectMask = VK_IMAGE_ASPECT_COLOR_BIT,
      .mipLevel = 0,
      .arrayLayer = 0,
   };
   wsi->GetImageSubresourceLayout(chain->device, image->image,
                                  &image_subresource, &image_layout);

   const struct wsi_memory_allocate_info memory_wsi_info = {
      .sType = VK_STRUCTURE_TYPE_WSI_MEMORY_ALLOCATE_INFO_MESA,
      .pNext = NULL,
      .implicit_sync = true,
   };
   const VkExportMemoryAllocateInfoKHR memory_export_info = {
      .sType = VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO_KHR,
      .pNext = &memory_wsi_info,
      .handleTypes = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
   };
   const VkMemoryDedicatedAllocateInfoKHR memory_dedicated_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_DEDICATED_ALLOCATE_INFO_KHR,
      .pNext = &memory_export_info,
      .image = image->image,
      .buffer = VK_NULL_HANDLE,
   };
   const VkMemoryAllocateInfo memory_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
      .pNext = &memory_dedicated_info,
      .allocationSize = reqs.size,
      .memoryTypeIndex = select_memory_type(wsi, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
                                            reqs.memoryTypeBits),
   };
   result = wsi->AllocateMemory(chain->device, &memory_info,
                                &chain->alloc, &image->memory);
   if (result != VK_SUCCESS)
      goto fail;

   result = wsi->BindImageMemory(chain->device, image->image,
                                 image->memory, 0);
   if (result != VK_SUCCESS)
      goto fail;

   const VkMemoryGetFdInfoKHR memory_get_fd_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_GET_FD_INFO_KHR,
      .pNext = NULL,
      .memory = image->memory,
      .handleType = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
   };
   int fd;
   result = wsi->GetMemoryFdKHR(chain->device, &memory_get_fd_info, &fd);
   if (result != VK_SUCCESS)
      goto fail;

   image->size = reqs.size;
   image->row_pitch = image_layout.rowPitch;
   image->offset = 0;
   image->fd = fd;

   return VK_SUCCESS;

fail:
   wsi_destroy_image(chain, image);

   return result;
}

#define WSI_PRIME_LINEAR_STRIDE_ALIGN 256

VkResult
wsi_create_prime_image(const struct wsi_swapchain *chain,
                       const VkSwapchainCreateInfoKHR *pCreateInfo,
                       struct wsi_image *image)
{
   const struct wsi_device *wsi = chain->wsi;
   VkResult result;

   memset(image, 0, sizeof(*image));

   const uint32_t cpp = vk_format_size(pCreateInfo->imageFormat);
   const uint32_t linear_stride = align_u32(pCreateInfo->imageExtent.width * cpp,
                                            WSI_PRIME_LINEAR_STRIDE_ALIGN);

   uint32_t linear_size = linear_stride * pCreateInfo->imageExtent.height;
   linear_size = align_u32(linear_size, 4096);

   const VkExternalMemoryBufferCreateInfoKHR prime_buffer_external_info = {
      .sType = VK_STRUCTURE_TYPE_EXTERNAL_MEMORY_BUFFER_CREATE_INFO_KHR,
      .pNext = NULL,
      .handleTypes = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
   };
   const VkBufferCreateInfo prime_buffer_info = {
      .sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO,
      .pNext = &prime_buffer_external_info,
      .size = linear_size,
      .usage = VK_BUFFER_USAGE_TRANSFER_DST_BIT,
      .sharingMode = VK_SHARING_MODE_EXCLUSIVE,
   };
   result = wsi->CreateBuffer(chain->device, &prime_buffer_info,
                              &chain->alloc, &image->prime.buffer);
   if (result != VK_SUCCESS)
      goto fail;

   VkMemoryRequirements reqs;
   wsi->GetBufferMemoryRequirements(chain->device, image->prime.buffer, &reqs);
   assert(reqs.size <= linear_size);

   const struct wsi_memory_allocate_info memory_wsi_info = {
      .sType = VK_STRUCTURE_TYPE_WSI_MEMORY_ALLOCATE_INFO_MESA,
      .pNext = NULL,
      .implicit_sync = true,
   };
   const VkExportMemoryAllocateInfoKHR prime_memory_export_info = {
      .sType = VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO_KHR,
      .pNext = &memory_wsi_info,
      .handleTypes = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
   };
   const VkMemoryDedicatedAllocateInfoKHR prime_memory_dedicated_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_DEDICATED_ALLOCATE_INFO_KHR,
      .pNext = &prime_memory_export_info,
      .image = VK_NULL_HANDLE,
      .buffer = image->prime.buffer,
   };
   const VkMemoryAllocateInfo prime_memory_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
      .pNext = &prime_memory_dedicated_info,
      .allocationSize = linear_size,
      .memoryTypeIndex = select_memory_type(wsi, 0, reqs.memoryTypeBits),
   };
   result = wsi->AllocateMemory(chain->device, &prime_memory_info,
                                &chain->alloc, &image->prime.memory);
   if (result != VK_SUCCESS)
      goto fail;

   result = wsi->BindBufferMemory(chain->device, image->prime.buffer,
                                  image->prime.memory, 0);
   if (result != VK_SUCCESS)
      goto fail;

   const VkImageCreateInfo image_info = {
      .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
      .pNext = NULL,
      .flags = 0,
      .imageType = VK_IMAGE_TYPE_2D,
      .format = pCreateInfo->imageFormat,
      .extent = {
         .width = pCreateInfo->imageExtent.width,
         .height = pCreateInfo->imageExtent.height,
         .depth = 1,
      },
      .mipLevels = 1,
      .arrayLayers = 1,
      .samples = VK_SAMPLE_COUNT_1_BIT,
      .tiling = VK_IMAGE_TILING_OPTIMAL,
      .usage = pCreateInfo->imageUsage | VK_IMAGE_USAGE_TRANSFER_SRC_BIT,
      .sharingMode = pCreateInfo->imageSharingMode,
      .queueFamilyIndexCount = pCreateInfo->queueFamilyIndexCount,
      .pQueueFamilyIndices = pCreateInfo->pQueueFamilyIndices,
      .initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
   };
   result = wsi->CreateImage(chain->device, &image_info,
                             &chain->alloc, &image->image);
   if (result != VK_SUCCESS)
      goto fail;

   wsi->GetImageMemoryRequirements(chain->device, image->image, &reqs);

   const VkMemoryDedicatedAllocateInfoKHR memory_dedicated_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_DEDICATED_ALLOCATE_INFO_KHR,
      .pNext = NULL,
      .image = image->image,
      .buffer = VK_NULL_HANDLE,
   };
   const VkMemoryAllocateInfo memory_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
      .pNext = &memory_dedicated_info,
      .allocationSize = reqs.size,
      .memoryTypeIndex = select_memory_type(wsi, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
                                            reqs.memoryTypeBits),
   };
   result = wsi->AllocateMemory(chain->device, &memory_info,
                                &chain->alloc, &image->memory);
   if (result != VK_SUCCESS)
      goto fail;

   result = wsi->BindImageMemory(chain->device, image->image,
                                 image->memory, 0);
   if (result != VK_SUCCESS)
      goto fail;

   image->prime.blit_cmd_buffers =
      vk_zalloc(&chain->alloc,
                sizeof(VkCommandBuffer) * wsi->queue_family_count, 8,
                VK_SYSTEM_ALLOCATION_SCOPE_OBJECT);
   if (!image->prime.blit_cmd_buffers)
      goto fail;

   for (uint32_t i = 0; i < wsi->queue_family_count; i++) {
      const VkCommandBufferAllocateInfo cmd_buffer_info = {
         .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
         .pNext = NULL,
         .commandPool = chain->cmd_pools[i],
         .level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
         .commandBufferCount = 1,
      };
      result = wsi->AllocateCommandBuffers(chain->device, &cmd_buffer_info,
                                           &image->prime.blit_cmd_buffers[i]);
      if (result != VK_SUCCESS)
         goto fail;

      const VkCommandBufferBeginInfo begin_info = {
         .sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
      };
      wsi->BeginCommandBuffer(image->prime.blit_cmd_buffers[i], &begin_info);

      struct VkBufferImageCopy buffer_image_copy = {
         .bufferOffset = 0,
         .bufferRowLength = linear_stride / cpp,
         .bufferImageHeight = 0,
         .imageSubresource = {
            .aspectMask = VK_IMAGE_ASPECT_COLOR_BIT,
            .mipLevel = 0,
            .baseArrayLayer = 0,
            .layerCount = 1,
         },
         .imageOffset = { .x = 0, .y = 0, .z = 0 },
         .imageExtent = {
            .width = pCreateInfo->imageExtent.width,
            .height = pCreateInfo->imageExtent.height,
            .depth = 1,
         },
      };
      wsi->CmdCopyImageToBuffer(image->prime.blit_cmd_buffers[i],
                                image->image,
                                VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
                                image->prime.buffer,
                                1, &buffer_image_copy);

      result = wsi->EndCommandBuffer(image->prime.blit_cmd_buffers[i]);
      if (result != VK_SUCCESS)
         goto fail;
   }

   const VkMemoryGetFdInfoKHR linear_memory_get_fd_info = {
      .sType = VK_STRUCTURE_TYPE_MEMORY_GET_FD_INFO_KHR,
      .pNext = NULL,
      .memory = image->prime.memory,
      .handleType = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
   };
   int fd;
   result = wsi->GetMemoryFdKHR(chain->device, &linear_memory_get_fd_info, &fd);
   if (result != VK_SUCCESS)
      goto fail;

   image->size = linear_size;
   image->row_pitch = linear_stride;
   image->offset = 0;
   image->fd = fd;

   return VK_SUCCESS;

fail:
   wsi_destroy_image(chain, image);

   return result;
}

void
wsi_destroy_image(const struct wsi_swapchain *chain,
                  struct wsi_image *image)
{
   const struct wsi_device *wsi = chain->wsi;

   if (image->prime.blit_cmd_buffers) {
      for (uint32_t i = 0; i < wsi->queue_family_count; i++) {
         wsi->FreeCommandBuffers(chain->device, chain->cmd_pools[i],
                                 1, &image->prime.blit_cmd_buffers[i]);
      }
      vk_free(&chain->alloc, image->prime.blit_cmd_buffers);
   }

   wsi->FreeMemory(chain->device, image->memory, &chain->alloc);
   wsi->DestroyImage(chain->device, image->image, &chain->alloc);
   wsi->FreeMemory(chain->device, image->prime.memory, &chain->alloc);
   wsi->DestroyBuffer(chain->device, image->prime.buffer, &chain->alloc);
}

VkResult
wsi_prime_image_blit_to_linear(const struct wsi_swapchain *chain,
                               struct wsi_image *image,
                               VkQueue queue,
                               uint32_t waitSemaphoreCount,
                               const VkSemaphore *pWaitSemaphores)
{
   uint32_t queue_family = chain->wsi->queue_get_family_index(queue);

   VkPipelineStageFlags stage_flags = VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT;
   const VkSubmitInfo submit_info = {
      .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
      .pNext = NULL,
      .waitSemaphoreCount = waitSemaphoreCount,
      .pWaitSemaphores = pWaitSemaphores,
      .pWaitDstStageMask = &stage_flags,
      .commandBufferCount = 1,
      .pCommandBuffers = &image->prime.blit_cmd_buffers[queue_family],
      .signalSemaphoreCount = 0,
      .pSignalSemaphores = NULL,
   };
   return chain->wsi->QueueSubmit(queue, 1, &submit_info, VK_NULL_HANDLE);
}

VkResult
wsi_common_get_images(VkSwapchainKHR _swapchain,
                      uint32_t *pSwapchainImageCount,
                      VkImage *pSwapchainImages)
{
   WSI_FROM_HANDLE(wsi_swapchain, swapchain, _swapchain);
   VK_OUTARRAY_MAKE(images, pSwapchainImages, pSwapchainImageCount);

   for (uint32_t i = 0; i < swapchain->image_count; i++) {
      vk_outarray_append(&images, image) {
         *image = swapchain->get_wsi_image(swapchain, i)->image;
      }
   }

   return vk_outarray_status(&images);
}

VkResult
wsi_common_queue_present(const struct wsi_device *wsi,
                         VkDevice device,
                         VkQueue queue,
                         int queue_family_index,
                         const VkPresentInfoKHR *pPresentInfo)
{
   VkResult final_result = VK_SUCCESS;

   const VkPresentRegionsKHR *regions =
      vk_find_struct_const(pPresentInfo->pNext, PRESENT_REGIONS_KHR);

   for (uint32_t i = 0; i < pPresentInfo->swapchainCount; i++) {
      WSI_FROM_HANDLE(wsi_swapchain, swapchain, pPresentInfo->pSwapchains[i]);
      VkResult result;

      if (swapchain->fences[0] == VK_NULL_HANDLE) {
         const VkFenceCreateInfo fence_info = {
            .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO,
            .pNext = NULL,
            .flags = 0,
         };
         result = wsi->CreateFence(device, &fence_info,
                                   &swapchain->alloc,
                                   &swapchain->fences[0]);
         if (result != VK_SUCCESS)
            goto fail_present;
      } else {
         wsi->ResetFences(device, 1, &swapchain->fences[0]);
      }

      VkSubmitInfo submit_info = {
         .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
         .pNext = NULL,
      };
      VkPipelineStageFlags *stage_flags = NULL;
      if (i == 0) {
         /* We only need/want to wait on semaphores once.  After that, we're
          * guaranteed ordering since it all happens on the same queue.
          */
         submit_info.waitSemaphoreCount = pPresentInfo->waitSemaphoreCount,
         submit_info.pWaitSemaphores = pPresentInfo->pWaitSemaphores,

         /* Set up the pWaitDstStageMasks */
         stage_flags = vk_alloc(&swapchain->alloc,
                                sizeof(VkPipelineStageFlags) *
                                pPresentInfo->waitSemaphoreCount,
                                8,
                                VK_SYSTEM_ALLOCATION_SCOPE_COMMAND);
         if (!stage_flags) {
            result = VK_ERROR_OUT_OF_HOST_MEMORY;
            goto fail_present;
         }
         for (uint32_t s = 0; s < pPresentInfo->waitSemaphoreCount; s++)
            stage_flags[s] = VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT;

         submit_info.pWaitDstStageMask = stage_flags;
      }
      result = wsi->QueueSubmit(queue, 1, &submit_info, swapchain->fences[0]);
      vk_free(&swapchain->alloc, stage_flags);
      if (result != VK_SUCCESS)
         goto fail_present;

      const VkPresentRegionKHR *region = NULL;
      if (regions && regions->pRegions)
         region = &regions->pRegions[i];

      result = swapchain->queue_present(swapchain,
                                        queue,
                                        pPresentInfo->waitSemaphoreCount,
                                        pPresentInfo->pWaitSemaphores,
                                        pPresentInfo->pImageIndices[i],
                                        region);
      if (result != VK_SUCCESS)
         goto fail_present;

      VkFence last = swapchain->fences[2];
      swapchain->fences[2] = swapchain->fences[1];
      swapchain->fences[1] = swapchain->fences[0];
      swapchain->fences[0] = last;

      if (last != VK_NULL_HANDLE) {
         wsi->WaitForFences(device, 1, &last, true, 1);
      }

   fail_present:
      if (pPresentInfo->pResults != NULL)
         pPresentInfo->pResults[i] = result;

      /* Let the final result be our first unsuccessful result */
      if (final_result == VK_SUCCESS)
         final_result = result;
   }

   return final_result;
}