From a9fdf5f933a6f2b358fad0194b1287b67f6704b1 Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Tue, 22 Aug 2023 16:36:18 +0300
Subject: [PATCH] thunderbolt: Check that lane 1 is in CL0 before enabling lane bonding
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Git-commit: a9fdf5f933a6f2b358fad0194b1287b67f6704b1
Patch-mainline: v6.6-rc6
References: git-fixes

Marek reported that when BlackMagic UltraStudio device is connected the
kernel repeatedly tries to enable lane bonding without success making
the device non-functional. It looks like the device does not have lane 1
connected at all so even though it is enabled we should not try to bond
the lanes. For this reason check that lane 1 is in fact CL0 (connected,
active) before attempting to bond the lanes.

Reported-by: Marek Šanta <teslan223@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217737
Cc: stable@vger.kernel.org
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/thunderbolt/switch.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2607,6 +2607,13 @@ int tb_switch_lane_bonding_enable(struct
 	    !tb_port_is_width_supported(down, 2))
 		return 0;
 
+	/*
+	 * Both lanes need to be in CL0. Here we assume lane 0 already be in
+	 * CL0 and check just for lane 1.
+	 */
+	if (tb_wait_for_port(down->dual_link_port, false) <= 0)
+		return -ENOTCONN;
+
 	ret = tb_port_lane_bonding_enable(up);
 	if (ret) {
 		tb_port_warn(up, "failed to enable lane bonding\n");