thunderbolt: Check that lane 1 is in CL0 before enabling lane bonding

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>

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 9699d167d522d93c643909be36b32ef87639e05a..55698a0978f03a03573cf2d7eefafd56d74a3a59 100644 (file)
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2763,6 +2763,13 @@ int tb_switch_lane_bonding_enable(struct tb_switch *sw)
            !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");