diff --git a/hw/dv/sv/jtag_agent/jtag_agent_cfg.sv b/hw/dv/sv/jtag_agent/jtag_agent_cfg.sv
index 8ddfc46fcf1d8..79a1b27e24aa2 100644
--- a/hw/dv/sv/jtag_agent/jtag_agent_cfg.sv
+++ b/hw/dv/sv/jtag_agent/jtag_agent_cfg.sv
@@ -28,6 +28,16 @@ class jtag_agent_cfg extends dv_base_agent_cfg;
   // This knob can bypass default 1 cycle initial delay of 'driver.drive_jtag_req()' task.
   // Use this knob only for the necessary tests.
   bit     min_rti = 0;
+
+  // This JTAG driver expects to control the JTAG interface clock (TCK), which it does by setting
+  // tck_en to 0 or 1. If rtc_length is positive, it gives a number of TCK cycles to "run to clear"
+  // (where we expect to be in the RunTest/IDLE state) before disabling the clock.
+  //
+  // This allows safe interactions with things like DMI operations, where we expect CDC to convert
+  // between the JTAG clock and a system clock. This only works when TCK is running!
+  int unsigned rtc_length = 0;
+
+
   `uvm_object_utils_begin(jtag_agent_cfg)
     `uvm_field_object(jtag_dtm_ral, UVM_DEFAULT)
   `uvm_object_utils_end
diff --git a/hw/dv/sv/jtag_agent/jtag_driver.sv b/hw/dv/sv/jtag_agent/jtag_driver.sv
index 7b50a4b0763aa..64992aba10c8c 100644
--- a/hw/dv/sv/jtag_agent/jtag_driver.sv
+++ b/hw/dv/sv/jtag_agent/jtag_driver.sv
@@ -27,6 +27,10 @@ class jtag_driver extends dv_base_driver #(jtag_item, jtag_agent_cfg);
   // without going to Run-Test-Idle), this extra cycle must be skipped
   protected bit                   exit_to_rti_dr_past = 1;
 
+  // A state flag used for controlling when we disable TCK if rtc_length is positive (see
+  // release_tck() for details)
+  protected bit tck_in_use = 1'b0;
+
   // Reset internal model of interface state
   //
   // This is needed on a genuine interface reset, but is also needed when we find out our interface
@@ -52,6 +56,37 @@ class jtag_driver extends dv_base_driver #(jtag_item, jtag_agent_cfg);
     exit_to_rti_dr_past = 1;
   endfunction
 
+  // Turn on TCK in the jtag_if
+  //
+  // This "acquires TCK" by setting tck_in_use (and checks that it was false beforehand).
+  virtual function void enable_tck();
+    `DV_CHECK_FATAL(!tck_in_use)
+    tck_in_use = 1'b1;
+    cfg.vif.tck_en <= 1'b1;
+  endfunction
+
+  // Turn off TCK in the jtag_if.
+  //
+  // If rtc_length is positive, wait that many ticks before actually turning TCK off. Clear
+  // tck_in_use at the start (after checking it was true). If it becomes true while we're waiting,
+  // return without making any change since another process now requires the clock running.
+  virtual task release_tck();
+    `DV_CHECK_FATAL(tck_in_use)
+    tck_in_use = 1'b0;
+    fork begin
+      if (cfg.rtc_length > 0) begin
+        fork begin : isolation_fork
+          fork
+            cfg.vif.wait_tck(cfg.rtc_length);
+            @(tck_in_use);
+          join_any
+          disable fork;
+        end join
+      end
+      if (!tck_in_use) cfg.vif.tck_en <= 1'b0;
+    end join_none
+  endtask
+
   virtual task reset_signals();
     fork
       begin
@@ -96,8 +131,9 @@ class jtag_driver extends dv_base_driver #(jtag_item, jtag_agent_cfg);
         // Make sure that we're aligned to HOST_CB (on the negedge of TCK). If we have just finished
         // the previous item, this delay is going to add a cycle of TCK, but we're in RunTest/IDLE,
         // so it won't cause any harm.
-        cfg.vif.tck_en <= 1'b1;
+        enable_tck();
         @(`HOST_CB);
+        release_tck();
 
         `uvm_info(`gfn, req.sprint(uvm_default_line_printer), UVM_HIGH)
         `DV_SPINWAIT_EXIT(drive_jtag_req(req, rsp);,
@@ -131,7 +167,7 @@ class jtag_driver extends dv_base_driver #(jtag_item, jtag_agent_cfg);
       fork
         begin
           // Enable clock
-          cfg.vif.tck_en <= 1'b1;
+          enable_tck();
           `HOST_CB.tms <= 1'b0;
           @(`HOST_CB);
           // Go to Test Logic Reset
@@ -152,7 +188,7 @@ class jtag_driver extends dv_base_driver #(jtag_item, jtag_agent_cfg);
 
   // drive jtag req and retrieve rsp
   virtual task drive_jtag_req(jtag_item req, jtag_item rsp);
-    cfg.vif.tck_en <= 1'b1;
+    enable_tck();
     if (req.reset_tap_fsm) begin
       drive_jtag_test_logic_reset();
     end
@@ -185,7 +221,7 @@ class jtag_driver extends dv_base_driver #(jtag_item, jtag_agent_cfg);
                     req.dr_pause_cycle,
                     req.exit_to_rti_dr);
     end
-    cfg.vif.tck_en <= 1'b0;
+    release_tck();
   endtask
 
   task drive_jtag_ir(int len,
diff --git a/hw/dv/sv/jtag_dmi_agent/jtag_dmi_reg_frontdoor.sv b/hw/dv/sv/jtag_dmi_agent/jtag_dmi_reg_frontdoor.sv
index 1d82d9dd19ff5..83802fd56692a 100644
--- a/hw/dv/sv/jtag_dmi_agent/jtag_dmi_reg_frontdoor.sv
+++ b/hw/dv/sv/jtag_dmi_agent/jtag_dmi_reg_frontdoor.sv
@@ -26,6 +26,10 @@ class jtag_dmi_reg_frontdoor extends uvm_reg_frontdoor;
     jtag_dtm_reg_block  jtag_dtm_ral = jtag_agent_cfg_h.jtag_dtm_ral;
     jtag_dmi_op_rsp_e   op_rsp;
 
+    // Configure the JTAG agent to have a positive run-to-clear length, ensuring that DMI operations
+    // make it from dmi_jtag to dm_top and back again before TCK stops.
+    jtag_agent_cfg_h.rtc_length = 4;
+
     // If the JTAG agent is sitting in reset, print a debug message and exit early
     if (jtag_agent_cfg_h.in_reset) begin
       `uvm_info(`gfn, "DMI CSR req skipped due to reset", UVM_HIGH)