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AR# 60653

2014.2 Vivado, ATG - AXI Traffic Generator repeat count cannot exceed 0xFFFFF


For an AXI traffic generator configured with OP_REPEAT and Increment ADDRMODE, write CMD is repeated as expected when repeat count (bit[23:0]) is not more than 0xFFFFF.
When repeat count is 0x100000 or 0x100001, CMD is repeated only once.

When repeat count is more than 0x100001, CMD is repeated 0x100000 times and then hangs.


In the core source file "axi_traffic_gen_v2_0_paramram_wrap.v" on line 777, there is the following code which checks only bit[19:1] to find a repeat count >1.
This explains why CMD only repeats once when the repeat count is 0x100000 or 0x100001:

   wire        param_cmdw_repeatop_valid = newcmdw_param_valid &&
                                           paramram_mw_regslice[19:1] != 16'h0 && // need value >1
                                           paramram_mw_regslice[31:29] == `SQOP_REPEATOP;

On line 846, there is the following code, where param_cmdw_submitcnt_ff is 20 bit register and param_cmdw_count_minus1_ff is 24 bit register.

               if (param_cmdw_repeatop_valid && (param_cmdw_submitcnt_ff != param_cmdw_count_minus1_ff))
                 param_cmdw_disable_submitincr <= 1'b1;

They cannot compare with each other.
This might be the reason why CMD is repeated 0x100000 times and becomes stuck.

This issue is fixed starting in Vivado 2014.3.
AR# 60653
Date 03/26/2015
Status Active
Type General Article
  • Zynq-7000
  • Kintex-7
  • AXI Traffic Generator
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