[GitHub] [tvm] kparzysz-quic commented on a diff in pull request #12411: [Hexagon] Asynchronous DMA support

[GitBox <gi...@apache.org>]

kparzysz-quic commented on code in PR #12411:
URL: https://github.com/apache/tvm/pull/12411#discussion_r949140383


##########
src/runtime/hexagon/hexagon_user_dma.cc:
##########
@@ -90,32 +78,80 @@ int hexagon_user_dma_1d_sync_helper(void* dst, void* src, uint32_t length) {
   dma_desc_set_src(dma_desc, src32);
   dma_desc_set_dst(dma_desc, dst32);
 
-  dmstart(dma_desc);
-  unsigned int status = dmwait() & DM0_STATUS_MASK;
-  unsigned int done = dma_desc_get_done(dma_desc);
+  // only for first DMA
+  if (first_dma_) {
+    // reset DMA engine
+    auto status = Init();
+    if (status != DM0_STATUS_IDLE) {
+      return DMA_FAILURE;
+    }
+
+    // `dmstart` first descriptor
+    dmstart(dma_desc);
+    first_dma_ = false;
+  } else {
+    // `dmlink` descriptor to tail
+    dmlink(dma_descriptors_.back(), dma_desc);

Review Comment:
   There is not limit that I'm aware of.



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