Merge tag 'thunderbolt-for-v6.12-rc5' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt into usb-linus

Mika writes:

thunderbolt: Fixes for v6.12-rc5

This includes following USB4/Thunderbolt fixes for v6.12-rc5:

  - Fix KASAN reported stack out-of-bounds read
  - Honor Time Management Unit (TMU) requirements in the domain when
    configuring TMU mode of a newly plugged router.

Both have been in linux-next with no reported issues.

* tag 'thunderbolt-for-v6.12-rc5' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt:
  thunderbolt: Honor TMU requirements in the domain when setting TMU mode
  thunderbolt: Fix KASAN reported stack out-of-bounds read in tb_retimer_scan()

Author: gregkh

drivers/thunderbolt/retimer.c

@@ -516,7 +516,7 @@ int tb_retimer_scan(struct tb_port *port, bool add)
 	 */
 	tb_retimer_set_inbound_sbtx(port);
 
-	for (i = 1; i <= TB_MAX_RETIMER_INDEX; i++) {
+	for (max = 1, i = 1; i <= TB_MAX_RETIMER_INDEX; i++) {
 		/*
 		 * Last retimer is true only for the last on-board
 		 * retimer (the one connected directly to the Type-C
@@ -527,9 +527,10 @@ int tb_retimer_scan(struct tb_port *port, bool add)
 			last_idx = i;
 		else if (ret < 0)
 			break;
+
+		max = i;
 	}
 
-	max = i;
 	ret = 0;
 
 	/* Add retimers if they do not exist already */

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;