From 480713b1ba8eac4617936f8404da34bda991c30e Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Mon, 13 Nov 2023 12:49:13 +0200
Subject: [PATCH] thunderbolt: Only add device router DP IN to the head of the
DP resource list
Git-commit: 480713b1ba8eac4617936f8404da34bda991c30e
References: jsc#PED-6054
Patch-mainline: v6.7-rc3
When pairing DP IN and DP OUT adapters for DisplayPort tunneling, we
should prioritize the possible external GPU DP IN adapters to take
advantage of the its capabilities. However the commit in question did
this for host router DP IN adapters too and that changes ordering of the
initial DP IN resources in such way that resuming from suspend may end
up using different resource and that may confuse the user.
Fix this so that we only put DP IN adapters of device routers to the top
of the resource list and leave host routers as is.
Fixes: 274baf695b08 ("thunderbolt: Add DP IN added last in the head of the list of DP resources")
Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/thunderbolt/tb.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 5acdeb766860..fd49f86e0353 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -213,7 +213,17 @@ static void tb_add_dp_resources(struct tb_switch *sw)
if (!tb_switch_query_dp_resource(sw, port))
continue;
- list_add(&port->list, &tcm->dp_resources);
+ /*
+ * If DP IN on device router exist, position it at the
+ * beginning of the DP resources list, so that it is used
+ * before DP IN of the host router. This way external GPU(s)
+ * will be prioritized when pairing DP IN to a DP OUT.
+ */
+ if (tb_route(sw))
+ list_add(&port->list, &tcm->dp_resources);
+ else
+ list_add_tail(&port->list, &tcm->dp_resources);
+
tb_port_dbg(port, "DP IN resource available\n");
}
}
--
2.43.0