thunderbolt: Make tb_switch_clx_disable() return CL states that were enabled

This allows us to disable all CL states temporarily when running lane
margining and then return back the previously enabled states.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/clx.c

@@ -317,6 +317,9 @@ int tb_switch_clx_enable(struct tb_switch *sw, unsigned int clx)
 	struct tb_port *up, *down;
 	int ret;
 
+	if (!clx)
+		return 0;
+
 	if (!validate_mask(clx))
 		return -EINVAL;
 
@@ -380,7 +383,8 @@ int tb_switch_clx_enable(struct tb_switch *sw, unsigned int clx)
  * Disables all CL states of the given router. Can be called on any
  * router and if the states were not enabled already does nothing.
  *
- * Returns %0 on success or an error code on failure.
+ * Returns the CL states that were disabled or negative errno in case of
+ * failure.
  */
 int tb_switch_clx_disable(struct tb_switch *sw)
 {
@@ -408,5 +412,5 @@ int tb_switch_clx_disable(struct tb_switch *sw)
 	sw->clx = 0;
 
 	tb_sw_dbg(sw, "CLx: %s disabled\n", clx_name(clx));
-	return 0;
+	return clx;
 }

drivers/thunderbolt/debugfs.c

@@ -553,8 +553,9 @@ static int margining_run_write(void *data, u64 val)
 	struct usb4_port *usb4 = port->usb4;
 	struct tb_switch *sw = port->sw;
 	struct tb_margining *margining;
+	struct tb_switch *down_sw;
 	struct tb *tb = sw->tb;
-	int ret;
+	int ret, clx;
 
 	if (val != 1)
 		return -EINVAL;
@@ -566,15 +567,24 @@ static int margining_run_write(void *data, u64 val)
 		goto out_rpm_put;
 	}
 
-	/*
-	 * CL states may interfere with lane margining so inform the user know
-	 * and bail out.
-	 */
-	if (tb_port_clx_is_enabled(port, TB_CL1 | TB_CL2)) {
-		tb_port_warn(port,
-			     "CL states are enabled, Disable them with clx=0 and re-connect\n");
-		ret = -EINVAL;
-		goto out_unlock;
+	if (tb_is_upstream_port(port))
+		down_sw = sw;
+	else if (port->remote)
+		down_sw = port->remote->sw;
+	else
+		down_sw = NULL;
+
+	if (down_sw) {
+		/*
+		 * CL states may interfere with lane margining so
+		 * disable them temporarily now.
+		 */
+		ret = tb_switch_clx_disable(down_sw);
+		if (ret < 0) {
+			tb_sw_warn(down_sw, "failed to disable CL states\n");
+			goto out_unlock;
+		}
+		clx = ret;
 	}
 
 	margining = usb4->margining;
@@ -586,7 +596,7 @@ static int margining_run_write(void *data, u64 val)
 					  margining->right_high,
 					  USB4_MARGIN_SW_COUNTER_CLEAR);
 		if (ret)
-			goto out_unlock;
+			goto out_clx;
 
 		ret = usb4_port_sw_margin_errors(port, &margining->results[0]);
 	} else {
@@ -600,6 +610,9 @@ static int margining_run_write(void *data, u64 val)
 					  margining->right_high, margining->results);
 	}
 
+out_clx:
+	if (down_sw)
+		tb_switch_clx_enable(down_sw, clx);
 out_unlock:
 	mutex_unlock(&tb->lock);
 out_rpm_put: