anv: Submit a dummy batch when only semaphores are provided.

Vulkan allows you to do a submit whose only job is to wait on and
trigger semaphores.  The easiest way for us to support that right
now is to insert a dummy execbuf.

Reviewed-by: Lionel Landwerlin <[email protected]>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/intel/vulkan/anv_queue.c b/src/intel/vulkan/anv_queue.c
index 9a0789ca322..039dfd7e2dc 100644
--- a/src/intel/vulkan/anv_queue.c
+++ b/src/intel/vulkan/anv_queue.c
@@ -159,6 +159,23 @@ VkResult anv_QueueSubmit(
    pthread_mutex_lock(&device->mutex);
 
    for (uint32_t i = 0; i < submitCount; i++) {
+      if (pSubmits[i].commandBufferCount == 0) {
+         /* If we don't have any command buffers, we need to submit a dummy
+          * batch to give GEM something to wait on.  We could, potentially,
+          * come up with something more efficient but this shouldn't be a
+          * common case.
+          */
+         result = anv_cmd_buffer_execbuf(device, NULL,
+                                         pSubmits[i].pWaitSemaphores,
+                                         pSubmits[i].waitSemaphoreCount,
+                                         pSubmits[i].pSignalSemaphores,
+                                         pSubmits[i].signalSemaphoreCount);
+         if (result != VK_SUCCESS)
+            goto out;
+
+         continue;
+      }
+
       for (uint32_t j = 0; j < pSubmits[i].commandBufferCount; j++) {
          ANV_FROM_HANDLE(anv_cmd_buffer, cmd_buffer,
                          pSubmits[i].pCommandBuffers[j]);