+ return &batch->validation_list[index];
+ }
+
+ return NULL;
+}
+
+/**
+ * Add a buffer to the current batch's validation list.
+ *
+ * You must call this on any BO you wish to use in this batch, to ensure
+ * that it's resident when the GPU commands execute.
+ */
+void
+iris_use_pinned_bo(struct iris_batch *batch,
+ struct iris_bo *bo,
+ bool writable)
+{
+ assert(bo->kflags & EXEC_OBJECT_PINNED);
+
+ /* Never mark the workaround BO with EXEC_OBJECT_WRITE. We don't care
+ * about the order of any writes to that buffer, and marking it writable
+ * would introduce data dependencies between multiple batches which share
+ * the buffer.
+ */
+ if (bo == batch->screen->workaround_bo)
+ writable = false;
+
+ struct drm_i915_gem_exec_object2 *existing_entry =
+ find_validation_entry(batch, bo);
+
+ if (existing_entry) {
+ /* The BO is already in the validation list; mark it writable */
+ if (writable)
+ existing_entry->flags |= EXEC_OBJECT_WRITE;
+
+ return;
+ }
+
+ if (bo != batch->bo) {
+ /* This is the first time our batch has seen this BO. Before we use it,
+ * we may need to flush and synchronize with other batches.
+ */
+ for (int b = 0; b < ARRAY_SIZE(batch->other_batches); b++) {
+ struct drm_i915_gem_exec_object2 *other_entry =
+ find_validation_entry(batch->other_batches[b], bo);
+
+ /* If the buffer is referenced by another batch, and either batch
+ * intends to write it, then flush the other batch and synchronize.
+ *
+ * Consider these cases:
+ *
+ * 1. They read, we read => No synchronization required.
+ * 2. They read, we write => Synchronize (they need the old value)
+ * 3. They write, we read => Synchronize (we need their new value)
+ * 4. They write, we write => Synchronize (order writes)
+ *
+ * The read/read case is very common, as multiple batches usually
+ * share a streaming state buffer or shader assembly buffer, and
+ * we want to avoid synchronizing in this case.
+ */
+ if (other_entry &&
+ ((other_entry->flags & EXEC_OBJECT_WRITE) || writable)) {
+ iris_batch_flush(batch->other_batches[b]);
+ iris_batch_add_syncpt(batch, batch->other_batches[b]->last_syncpt,
+ I915_EXEC_FENCE_WAIT);
+ }
+ }