Merge pull request #15813 from i-murzov:3.4-ocl-empty-platform

modules/core/src/ocl.cpp

@@ -2037,16 +2037,25 @@ struct Context::Impl
             0
         };
 
-        cl_uint i, nd0 = 0, nd = 0;
+        cl_uint nd0 = 0;
         int dtype = dtype0 & 15;
-        CV_OCL_DBG_CHECK(clGetDeviceIDs(pl, dtype, 0, 0, &nd0));
+        cl_int status = clGetDeviceIDs(pl, dtype, 0, NULL, &nd0);
+        if (status != CL_DEVICE_NOT_FOUND) // Not an error if platform has no devices
+        {
+            CV_OCL_DBG_CHECK_RESULT(status,
+                cv::format("clGetDeviceIDs(platform=%p, device_type=%d, num_entries=0, devices=NULL, numDevices=%p)", pl, dtype, &nd0).c_str());
+        }
+
+        if (nd0 == 0)
+            return;
 
         AutoBuffer<void*> dlistbuf(nd0*2+1);
         cl_device_id* dlist = (cl_device_id*)dlistbuf.data();
         cl_device_id* dlist_new = dlist + nd0;
         CV_OCL_DBG_CHECK(clGetDeviceIDs(pl, dtype, nd0, dlist, &nd0));
-        String name0;
 
+        cl_uint i, nd = 0;
+        String name0;
         for(i = 0; i < nd0; i++)
         {
             Device d(dlist[i]);
@@ -5944,7 +5953,12 @@ void convertFromImage(void* cl_mem_image, UMat& dst)
 static void getDevices(std::vector<cl_device_id>& devices, cl_platform_id platform)
 {
     cl_uint numDevices = 0;
-    CV_OCL_DBG_CHECK(clGetDeviceIDs(platform, (cl_device_type)Device::TYPE_ALL, 0, NULL, &numDevices));
+    cl_int status = clGetDeviceIDs(platform, (cl_device_type)Device::TYPE_ALL, 0, NULL, &numDevices);
+    if (status != CL_DEVICE_NOT_FOUND) // Not an error if platform has no devices
+    {
+        CV_OCL_DBG_CHECK_RESULT(status,
+            cv::format("clGetDeviceIDs(platform, Device::TYPE_ALL, num_entries=0, devices=NULL, numDevices=%p)", &numDevices).c_str());
+    }
 
     if (numDevices == 0)
     {