[PATCH 6.1 100/131] thunderbolt: Check that lane 1 is in CL0 before enabling lane bonding

Greg Kroah-Hartman
2023-10-16T09:04:57Z

From: Mika Westerberg <mika.westerberg@linux.intel.com>

commit a9fdf5f933a6f2b358fad0194b1287b67f6704b1 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/thunderbolt/switch.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2763,6 +2763,13 @@ 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");