1 files changed, 42 insertions, 6 deletions

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 10e719dd837c..4f777788e917 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -288,6 +288,24 @@ static void tb_increase_tmu_accuracy(struct tb_tunnel *tunnel)
 	device_for_each_child(&sw->dev, NULL, tb_increase_switch_tmu_accuracy);
 }
 
+static int tb_switch_tmu_hifi_uni_required(struct device *dev, void *not_used)
+{
+	struct tb_switch *sw = tb_to_switch(dev);
+
+	if (sw && tb_switch_tmu_is_enabled(sw) &&
+	    tb_switch_tmu_is_configured(sw, TB_SWITCH_TMU_MODE_HIFI_UNI))
+		return 1;
+
+	return device_for_each_child(dev, NULL,
+				     tb_switch_tmu_hifi_uni_required);
+}
+
+static bool tb_tmu_hifi_uni_required(struct tb *tb)
+{
+	return device_for_each_child(&tb->dev, NULL,
+				     tb_switch_tmu_hifi_uni_required) == 1;
+}
+
 static int tb_enable_tmu(struct tb_switch *sw)
 {
 	int ret;
@@ -302,12 +320,30 @@ static int tb_enable_tmu(struct tb_switch *sw)
 	ret = tb_switch_tmu_configure(sw,
 			TB_SWITCH_TMU_MODE_MEDRES_ENHANCED_UNI);
 	if (ret == -EOPNOTSUPP) {
-		if (tb_switch_clx_is_enabled(sw, TB_CL1))
-			ret = tb_switch_tmu_configure(sw,
-					TB_SWITCH_TMU_MODE_LOWRES);
-		else
-			ret = tb_switch_tmu_configure(sw,
-					TB_SWITCH_TMU_MODE_HIFI_BI);
+		if (tb_switch_clx_is_enabled(sw, TB_CL1)) {
+			/*
+			 * Figure out uni-directional HiFi TMU requirements
+			 * currently in the domain. If there are no
+			 * uni-directional HiFi requirements we can put the TMU
+			 * into LowRes mode.
+			 *
+			 * Deliberately skip bi-directional HiFi links
+			 * as these work independently of other links
+			 * (and they do not allow any CL states anyway).
+			 */
+			if (tb_tmu_hifi_uni_required(sw->tb))
+				ret = tb_switch_tmu_configure(sw,
+						TB_SWITCH_TMU_MODE_HIFI_UNI);
+			else
+				ret = tb_switch_tmu_configure(sw,
+						TB_SWITCH_TMU_MODE_LOWRES);
+		} else {
+			ret = tb_switch_tmu_configure(sw, TB_SWITCH_TMU_MODE_HIFI_BI);
+		}
+
+		/* If not supported, fallback to bi-directional HiFi */
+		if (ret == -EOPNOTSUPP)
+			ret = tb_switch_tmu_configure(sw, TB_SWITCH_TMU_MODE_HIFI_BI);
 	}
 	if (ret)
 		return ret;