thunderbolt: Skip discovery also in USB4 v2 host

If the host router is reset, there is no point running discovery as the
links are down. Furthermore this prevents CL-state enabling. For this
reason skip discovery in USB4 v2 host the same way we do with USB4 v1.
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/nhi.c

@@ -1221,7 +1221,7 @@ static void nhi_check_iommu(struct tb_nhi *nhi)
 		str_enabled_disabled(port_ok));
 }
 
-static bool nhi_reset(struct tb_nhi *nhi)
+static void nhi_reset(struct tb_nhi *nhi)
 {
 	ktime_t timeout;
 	u32 val;
@@ -1229,11 +1229,11 @@ static bool nhi_reset(struct tb_nhi *nhi)
 	val = ioread32(nhi->iobase + REG_CAPS);
 	/* Reset only v2 and later routers */
 	if (FIELD_GET(REG_CAPS_VERSION_MASK, val) < REG_CAPS_VERSION_2)
-		return false;
+		return;
 
 	if (!host_reset) {
 		dev_dbg(&nhi->pdev->dev, "skipping host router reset\n");
-		return false;
+		return;
 	}
 
 	iowrite32(REG_RESET_HRR, nhi->iobase + REG_RESET);
@@ -1244,14 +1244,12 @@ static bool nhi_reset(struct tb_nhi *nhi)
 		val = ioread32(nhi->iobase + REG_RESET);
 		if (!(val & REG_RESET_HRR)) {
 			dev_warn(&nhi->pdev->dev, "host router reset successful\n");
-			return true;
+			return;
 		}
 		usleep_range(10, 20);
 	} while (ktime_before(ktime_get(), timeout));
 
 	dev_warn(&nhi->pdev->dev, "timeout resetting host router\n");
-
-	return false;
 }
 
 static int nhi_init_msi(struct tb_nhi *nhi)
@@ -1333,7 +1331,6 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	struct device *dev = &pdev->dev;
 	struct tb_nhi *nhi;
 	struct tb *tb;
-	bool reset;
 	int res;
 
 	if (!nhi_imr_valid(pdev))
@@ -1367,12 +1364,7 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	nhi_check_quirks(nhi);
 	nhi_check_iommu(nhi);
-
-	/*
-	 * Only USB4 v2 hosts support host reset so if we already did
-	 * that then don't do it again when the domain is initialized.
-	 */
-	reset = nhi_reset(nhi) ? false : host_reset;
+	nhi_reset(nhi);
 
 	res = nhi_init_msi(nhi);
 	if (res)
@@ -1399,7 +1391,7 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	dev_dbg(dev, "NHI initialized, starting thunderbolt\n");
 
-	res = tb_domain_add(tb, reset);
+	res = tb_domain_add(tb, host_reset);
 	if (res) {
 		/*
 		 * At this point the RX/TX rings might already have been

drivers/thunderbolt/tb.c

@@ -2584,6 +2584,7 @@ static int tb_scan_finalize_switch(struct device *dev, void *data)
 static int tb_start(struct tb *tb, bool reset)
 {
 	struct tb_cm *tcm = tb_priv(tb);
+	bool discover = true;
 	int ret;
 
 	tb->root_switch = tb_switch_alloc(tb, &tb->dev, 0);
@@ -2629,9 +2630,13 @@ static int tb_start(struct tb *tb, bool reset)
 	 * reset the ports to handle it as new hotplug for USB4 v1
 	 * routers (for USB4 v2 and beyond we already do host reset).
 	 */
-	if (reset && usb4_switch_version(tb->root_switch) == 1) {
-		tb_switch_reset(tb->root_switch);
-	} else {
+	if (reset && tb_switch_is_usb4(tb->root_switch)) {
+		discover = false;
+		if (usb4_switch_version(tb->root_switch) == 1)
+			tb_switch_reset(tb->root_switch);
+	}
+
+	if (discover) {
 		/* Full scan to discover devices added before the driver was loaded. */
 		tb_scan_switch(tb->root_switch);
 		/* Find out tunnels created by the boot firmware */