UVM 1.1 User's Guide section 3.5.4

[Logger]

Section 3.5.4 of the UVM 1.1 User's Guide states that a resposne should be sent from the driver back to the sequencer using one of the following:

using the optional argument to item_done().

seq_item_port.item_done(rsp);

using the put_response() method.

seq_item_port.put_response(rsp);

or using the built-in analysis port in uvm_driver.

rsp_port.write(rsp);

Well that's nice. How about some description of when to use which one of these methods and why?

-Ryan

[pratta]

I had the same confusion about this. See this thread:

http://www.uvmworld.org/forums/showthread.php?243-seq_item_port.put_response%28rsp%29

From what I can tell, the seq_item_port.item_done(rsp) call should be done if the execution model is not pipelined. If the sequencer will only ever have a single transaction outstanding at a time this this is the method to use.

If you are using a pipelined communication model, then either the seq_item_port.put_response(rsp) or the rsp_port.write() method can be used. If using the response channel on seq_item_port then nothing more needs to be done to connect the sequencer to the driver. If using the rsp_port then in addition to connecting the seq_item_port, the containing agent must also connect the analysis ports. Which method you choose is up to you however - there are no guidelines about which method to use.