Merge pull request #21297 from rogday:div_fix

modules/dnn/src/onnx/onnx_importer.cpp

@@ -1472,7 +1472,16 @@ void ONNXImporter::parseMul(LayerParams& layerParams, const opencv_onnx::NodePro
         blob = blob.reshape(1, 1);
         if (blob.total() == 1) {
             float blob_value = blob.ptr<float>()[0];
-            float coeff = isDiv ? 1.0 / blob_value : blob_value;
+            float coeff = blob_value;
+            if (isDiv)
+            {
+                coeff = 1.f / blob_value;
+                if (constId == 0)
+                {
+                    // Power layer calculates (x*scale + shift)^power, so const/x -> (x * (1/const) + 0)^(-1)
+                    layerParams.set("power", -1.f);
+                }
+            }
             layerParams.set("scale", coeff);
             layerParams.type = "Power";
         }

modules/dnn/test/test_onnx_importer.cpp

@@ -1056,6 +1056,11 @@ TEST_P(Test_ONNX_layers, SubFromConst)
     testONNXModels("sub_from_const_broadcast");
 }
 
+TEST_P(Test_ONNX_layers, DivConst)
+{
+    testONNXModels("div_const");
+}
+
 INSTANTIATE_TEST_CASE_P(/*nothing*/, Test_ONNX_layers, dnnBackendsAndTargets());
 
 class Test_ONNX_nets : public Test_ONNX_layers