thunderbolt: Change TMU mode to HiFi uni-directional once DisplayPort tunneled

Here we configure TMU mode to HiFi uni-directional once DP tunnel
is created. This is due to accuracy requirement for DP tunneling
as appears in CM guide 1.0, section 7.3.2.
Due to Intel hardware limitation, once we changed the TMU mode to HiFi
uni-directional (when DP tunnel exists), we don't change TMU mode back to
normal uni-directional, even if DP tunnel is torn down later.
Signed-off-by: Gil Fine <gil.fine@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/tb.c

@@ -118,6 +118,13 @@ static void tb_switch_discover_tunnels(struct tb_switch *sw,
 		switch (port->config.type) {
 		case TB_TYPE_DP_HDMI_IN:
 			tunnel = tb_tunnel_discover_dp(tb, port, alloc_hopids);
+			/*
+			 * In case of DP tunnel exists, change host router's
+			 * 1st children TMU mode to HiFi for CL0s to work.
+			 */
+			if (tunnel)
+				tb_switch_enable_tmu_1st_child(tb->root_switch,
+						TB_SWITCH_TMU_RATE_HIFI);
 			break;
 
 		case TB_TYPE_PCIE_DOWN:
@@ -979,6 +986,12 @@ static void tb_tunnel_dp(struct tb *tb)
 
 	list_add_tail(&tunnel->list, &tcm->tunnel_list);
 	tb_reclaim_usb3_bandwidth(tb, in, out);
+	/*
+	 * In case of DP tunnel exists, change host router's 1st children
+	 * TMU mode to HiFi for CL0s to work.
+	 */
+	tb_switch_enable_tmu_1st_child(tb->root_switch, TB_SWITCH_TMU_RATE_HIFI);
+
 	return;
 
 err_free:

drivers/thunderbolt/tb.h

@@ -934,6 +934,8 @@ int tb_switch_tmu_enable(struct tb_switch *sw);
 void tb_switch_tmu_configure(struct tb_switch *sw,
 			     enum tb_switch_tmu_rate rate,
 			     bool unidirectional);
+void tb_switch_enable_tmu_1st_child(struct tb_switch *sw,
+				    enum tb_switch_tmu_rate rate);
 /**
  * tb_switch_tmu_is_enabled() - Checks if the specified TMU mode is enabled
  * @sw: Router whose TMU mode to check

drivers/thunderbolt/tmu.c

@@ -742,3 +742,32 @@ void tb_switch_tmu_configure(struct tb_switch *sw,
 	sw->tmu.unidirectional_request = unidirectional;
 	sw->tmu.rate_request = rate;
 }
+
+static int tb_switch_tmu_config_enable(struct device *dev, void *rate)
+{
+	if (tb_is_switch(dev)) {
+		struct tb_switch *sw = tb_to_switch(dev);
+
+		tb_switch_tmu_configure(sw, *(enum tb_switch_tmu_rate *)rate,
+					tb_switch_is_clx_enabled(sw, TB_CL1));
+		if (tb_switch_tmu_enable(sw))
+			tb_sw_dbg(sw, "fail switching TMU mode for 1st depth router\n");
+	}
+
+	return 0;
+}
+
+/**
+ * tb_switch_enable_tmu_1st_child - Configure and enable TMU for 1st chidren
+ * @sw: The router to configure and enable it's children TMU
+ * @rate: Rate of the TMU to configure the router's chidren to
+ *
+ * Configures and enables the TMU mode of 1st depth children of the specified
+ * router to the specified rate.
+ */
+void tb_switch_enable_tmu_1st_child(struct tb_switch *sw,
+				    enum tb_switch_tmu_rate rate)
+{
+	device_for_each_child(&sw->dev, &rate,
+			      tb_switch_tmu_config_enable);
+}