[GitHub] [tvm] tmoreau89 commented on a diff in pull request #13844: [Hexagon] Detect and flush "dirty" cache prior to DMA read with cache bypass enabled

["tmoreau89 (via GitHub)" <gi...@apache.org>]

tmoreau89 commented on code in PR #13844:
URL: https://github.com/apache/tvm/pull/13844#discussion_r1092480482


##########
src/tir/transforms/lower_async_dma.cc:
##########
@@ -192,19 +198,33 @@ class AsyncDMALowerer : public StmtExprMutator {
       // save queue ID for inspection in `wait` transform
       queue_ids_.insert(queue_id);
 
-      return Evaluate(Call(DataType::Int(32), builtin::dma_copy(),
-                           {queue_id,
-                            Call(DataType::Handle(), builtin::address_of(),
-                                 {BufferLoad(bufferstorenode->buffer, store_index)}),
-                            Call(DataType::Handle(), builtin::address_of(),
-                                 {BufferLoad(bufferloadnode->buffer, load_index)}),
-                            for_loop->extent * bufferloadnode->dtype.bytes(), dma_bypass_cache_}));
+      auto call_dma_copy =
+          Evaluate(Call(DataType::Int(32), builtin::dma_copy(),
+                        {queue_id,
+                         Call(DataType::Handle(), builtin::address_of(),
+                              {BufferLoad(bufferstorenode->buffer, store_index)}),
+                         Call(DataType::Handle(), builtin::address_of(),
+                              {BufferLoad(bufferloadnode->buffer, load_index)}),
+                         for_loop->extent * bufferloadnode->dtype.bytes(), dma_bypass_cache_}));
+
+      // if the buffer we are about to DMA was modified by the primfunc
+      // then we need to flush the buffer from the cache prior to the DMA

Review Comment:
   Definitely fine with getting this PR merged first before we plan to make broader changes. Janet's proposed plan seems quite sound.



-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: commits-unsubscribe@tvm.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org