From a206111288a331a4b37d4edbe5f5f7e5638af3aa Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Tue, 6 Jun 2017 15:24:54 +0300
Subject: [PATCH 02/34] thunderbolt: No need to read UID of the root switch on
 resume
Git-commit: 08a5e4cebec543bfa4a6d119fc18f0ed8fd9d8ce
Patch-mainline: v4.13-rc1
References: FATE#323948

The root switch is part of the host controller and cannot be physically
removed, so there is no point of reading UID again on resume in order to
check if the root switch is still the same.

Suggested-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/thunderbolt/switch.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index c6f30b1695a9..81f5164a6364 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -452,19 +452,26 @@ void tb_sw_set_unplugged(struct tb_switch *sw)
 int tb_switch_resume(struct tb_switch *sw)
 {
 	int i, err;
-	u64 uid;
 	tb_sw_info(sw, "resuming switch\n");
 
-	err = tb_drom_read_uid_only(sw, &uid);
-	if (err) {
-		tb_sw_warn(sw, "uid read failed\n");
-		return err;
-	}
-	if (sw != sw->tb->root_switch && sw->uid != uid) {
-		tb_sw_info(sw,
-			"changed while suspended (uid %#llx -> %#llx)\n",
-			sw->uid, uid);
-		return -ENODEV;
+	/*
+	 * Check for UID of the connected switches except for root
+	 * switch which we assume cannot be removed.
+	 */
+	if (tb_route(sw)) {
+		u64 uid;
+
+		err = tb_drom_read_uid_only(sw, &uid);
+		if (err) {
+			tb_sw_warn(sw, "uid read failed\n");
+			return err;
+		}
+		if (sw->uid != uid) {
+			tb_sw_info(sw,
+				"changed while suspended (uid %#llx -> %#llx)\n",
+				sw->uid, uid);
+			return -ENODEV;
+		}
 	}
 
 	/* upload configuration */
-- 
2.12.3