From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Mon, 26 Aug 2019 18:19:33 +0300
Subject: thunderbolt: Add default linking between lane adapters if not
 provided by DROM
Git-commit: 0d46c08d1ed4f7bb283c7315824f2bfe2c5e0fa9
Patch-mainline: v5.5-rc1
References: jsc#SLE-14130

We currently read how sibling lane adapter ports relate each other from
DROM (Device ROM). If the two lane adapter ports go through the same
physical connector these lanes can then be bonded together. However,
some cases DROM does not provide this information or it is missing
completely (host routers typically do not have DROM). In this case we
have hard-coded the relationship.

Expand this to work with both legacy devices where lane adapter ports 1
and 2, and 3 and 4 are always linked together, and with USB4 devices
where lane adapter 1 is always following lane adapter 0 or is disabled
completely (see USB4 section 5.2.1 for more information).

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/thunderbolt/eeprom.c | 11 -----------
 drivers/thunderbolt/switch.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
index ee5196479854..8dd7de0cc826 100644
--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -514,17 +514,6 @@ int tb_drom_read(struct tb_switch *sw)
 		 * no entries). Hardcode the configuration here.
 		 */
 		tb_drom_read_uid_only(sw, &sw->uid);
-
-		sw->ports[1].link_nr = 0;
-		sw->ports[2].link_nr = 1;
-		sw->ports[1].dual_link_port = &sw->ports[2];
-		sw->ports[2].dual_link_port = &sw->ports[1];
-
-		sw->ports[3].link_nr = 0;
-		sw->ports[4].link_nr = 1;
-		sw->ports[3].dual_link_port = &sw->ports[4];
-		sw->ports[4].dual_link_port = &sw->ports[3];
-
 		return 0;
 	}
 
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 12a63f86820e..205045caabdc 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -1936,6 +1936,36 @@ static int tb_switch_add_dma_port(struct tb_switch *sw)
 	return -ESHUTDOWN;
 }
 
+static void tb_switch_default_link_ports(struct tb_switch *sw)
+{
+	int i;
+
+	for (i = 1; i <= sw->config.max_port_number; i += 2) {
+		struct tb_port *port = &sw->ports[i];
+		struct tb_port *subordinate;
+
+		if (!tb_port_is_null(port))
+			continue;
+
+		/* Check for the subordinate port */
+		if (i == sw->config.max_port_number ||
+		    !tb_port_is_null(&sw->ports[i + 1]))
+			continue;
+
+		/* Link them if not already done so (by DROM) */
+		subordinate = &sw->ports[i + 1];
+		if (!port->dual_link_port && !subordinate->dual_link_port) {
+			port->link_nr = 0;
+			port->dual_link_port = subordinate;
+			subordinate->link_nr = 1;
+			subordinate->dual_link_port = port;
+
+			tb_sw_dbg(sw, "linked ports %d <-> %d\n",
+				  port->port, subordinate->port);
+		}
+	}
+}
+
 static bool tb_switch_lane_bonding_possible(struct tb_switch *sw)
 {
 	const struct tb_port *up = tb_upstream_port(sw);
@@ -2109,6 +2139,8 @@ int tb_switch_add(struct tb_switch *sw)
 			}
 		}
 
+		tb_switch_default_link_ports(sw);
+
 		ret = tb_switch_update_link_attributes(sw);
 		if (ret)
 			return ret;