problem about macro uvm_do_with()

[mrforever]

Hi, all

 

I have met such a problem, when i use uvm_do_with to start item, then it is stuck at uvm_do_with.

 

The hierarchy struct of the sequence is

v_seq

      |- cfg_seq

      |- sub_seq

      |- slv_seq

 

The hierarchy struct of the sequencer is

v_sqr

      |- cfg_sqr

      |- sub_sqr

      |- slv_sqr

 

pieces of code in test.sv

  task run_phase(uvm_phase phase); 
    //uvm_config_db#(uvm_phase)::set(this, "*", "starting_phase", phase); 
    for (int i = 0; i < num; i++) begin
      fork
        begin   
          env.v_seq[i].starting_phase = phase;
          env.v_seq[i].start(env.subenv[i].v_sqr);
        end
      join
    end  

    //set a drain-time for the environment if desired 
    phase.phase_done.set_drain_time(this, 50);
  endtask : run_phase

pieces of code in v_seq

  virtual task body()
  
   cfg_seq.start(p_sequencer.cfg_sqr, this);
    fork   
      begin : sub_seq // thread1 
        sub_seq.start(p_sequencer.sub_sqr, this);
      end     
      //begin : slave_seq // thread2 
      //  slv_seq.start(p_sequencer.slv_sqr, this);
      //end   
    join

  endtask
  ...

  // declare vsequencer as the p_sequencer of vsequence
    `uvm_declare_p_sequencer(vsequencer) 

pieces of code in sub_seq

  virtual task body();

    `uvm_info(get_type_name(),$sformatf("%0s starting...",
      get_sequence_path()), UVM_LOW)

    repeat(10) begin
      `uvm_do_with(req,
        { req.addr == `CFG_ADDR;
          req.req_typ == MWr; }) 
      get_response(rsp);
    end   

  endtask : body

pieces of code in v_sqr

class vsequencer extends uvm_sequencer;
  ...
  function void build_phase(uvm_phase phase);
    super.build_phase(phase);
    // instantiates sequencers and config_db
    cfg_sqr = config_sequencer::type_id::create("cfg_sqr", this);
    sub_sqr = sub_sequencer::type_id::create("sub_sqr", this);
    slv_sqr = slave_sequencer::type_id::create("slv_sqr", this);
  endfunction : build_phase
  ...
endclass: vsequencer

 

 

I find that it is stuck at line m_wait_for_arbitration_completed(req_s.request_id); of task wait_for_grant() in file uvm_sequencer_base.svh. Could anybody tell me the reason?

 

Thanks in advance!

[David Long]

Hi,

 

When you start a sequence item, either by calling the macro `uvm_do/`uvm_do_with or the tasks start_item/finish_item, it will block until it gets a response from the driver. How are you getting the sequence items in your driver? You should be calling either

 

 

seq_item_port.get(req);  //fetches sequence item then sends acknowledgement
 

 

 

or

 

 

seq_item_port.get_item(req);  //fetches sequence item
..
seq_item_port.item_done();  //sends acknowledgement
 

 

 

Regards,

Dave

[mrforever]

Hi,

 

When you start a sequence item, either by calling the macro `uvm_do/`uvm_do_with or the tasks start_item/finish_item, it will block until it gets a response from the driver. How are you getting the sequence items in your driver? You should be calling either

 

 

seq_item_port.get(req);  //fetches sequence item then sends acknowledgement
 

 

 

or

 

 

seq_item_port.get_item(req);  //fetches sequence item
..
seq_item_port.item_done();  //sends acknowledgement
 

 

 

Regards,

Dave

 

Hi Dave,

My driver has such implementations:

  virtual task run_phase(uvm_phase phase);
    my_item req;

    @(negedge duv_vif.rst);
    forever begin
      @(this.duv_vif.wfifo_if.fifo_wr);
      seq_item_port.get_next_item(req);
      $cast(sub_item, req.clone());
      port2rm.write(sub_item);          
      write_mem(sub_item);
      drive_desc_pkt(sub_item);
      seq_item_port.item_done();
    end
  endtask : run_phase

 

Is there any problem? 

[David Long]

Hi,

 

Some suggestions for possible problems in your driver and how to detect them::

 

virtual task run_phase(uvm_phase phase);
my_item req;

@(negedge duv_vif.rst);
 

 

 

Do you see the reset?

 

 

forever begin
@(this.duv_vif.wfifo_if.fifo_wr);
 

 

Do you see the fifo_wr change?

 

seq_item_port.get_next_item(req);
 

Try writing out a message to test if you get to this line

 

$cast(sub_item, req.clone());
 

 

 

Are any of the following methods blocking?

 

port2rm.write(sub_item);
write_mem(sub_item);
drive_desc_pkt(sub_item);
 

 

Try writing out a message to test if you get to this line

 

seq_item_port.item_done();
end
endtask : run_phase
 

 

Hope that helps.

 

Regards,

Dave

[uwes]

hi,

 

there are a couple of things to check. basically the sequencer-driver protocol is a two way handshake:

 

1. seq item waiting until it is arbitrated, randomized and send to the driver

2. the sqr waits till the driver returns with item_done()

 

first i would check on which side it is blocking (in the sqr or the driver or inbetween)

 

i would also check if there are special semaphores in the system which could block progress (registers for instance) which may block when a reset/phase jump was executed.

 

/uwe

 

[mrforever]

Hi,

 

Some suggestions for possible problems in your driver and how to detect them::

 

virtual task run_phase(uvm_phase phase);
my_item req;

@(negedge duv_vif.rst);
 

 

 

Do you see the reset?

 

 

forever begin
@(this.duv_vif.wfifo_if.fifo_wr);
 

 

Do you see the fifo_wr change?

 

seq_item_port.get_next_item(req);
 

Try writing out a message to test if you get to this line

 

$cast(sub_item, req.clone());
 

 

 

Are any of the following methods blocking?

 

port2rm.write(sub_item);
write_mem(sub_item);
drive_desc_pkt(sub_item);
 

 

Try writing out a message to test if you get to this line

 

seq_item_port.item_done();
end
endtask : run_phase
 

 

Hope that helps.

 

Regards,

Dave

Hi Dave,

 

I think i have found the problem, it's about setting sequencer. I used uvm_config_db::set and uvm_config_db::get to set the sequencer at first, unfortunately it doesn't work. Then I just used the way of assigning sqr directly, it works and the problem disappears.

 

Thanks for you!

Regards

[mrforever]

hi,

 

there are a couple of things to check. basically the sequencer-driver protocol is a two way handshake:

 

1. seq item waiting until it is arbitrated, randomized and send to the driver

2. the sqr waits till the driver returns with item_done()

 

first i would check on which side it is blocking (in the sqr or the driver or inbetween)

 

i would also check if there are special semaphores in the system which could block progress (registers for instance) which may block when a reset/phase jump was executed.

 

/uwe

Hi, 

I think that I have solved the problem, thanks.

mrforever