From 873e5bb9fbd99e4a26c448b5c7af942a6d7aa60d Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Mon, 1 Feb 2021 14:01:42 +0200
Subject: drm/dp_mst: Don't report ports connected if nothing is attached to
 them
Git-commit: 873e5bb9fbd99e4a26c448b5c7af942a6d7aa60d
Patch-mainline: v5.11
References: bsc#1152489

Reporting a port as connected if nothing is attached to them leads to
any i2c transactions on this port trying to use an uninitialized i2c
adapter, fix this.

Let's account for this case even if branch devices have no good reason
to report a port as plugged with their peer device type set to 'none'.

Fixes: db1a07956968 ("drm/dp_mst: Handle SST-only branch device case")
__References: https://gitlab.freedesktop.org/drm/intel/-/issues/2987
__References: https://gitlab.freedesktop.org/drm/intel/-/issues/1963
Cc: Wayne Lin <Wayne.Lin@amd.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: <stable@vger.kernel.org> # v5.5+
Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reported-by: Thiago Macieira <gitlab@gitlab.freedesktop.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210201120145.350258-1-imre.deak@intel.com
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---

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---
 drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 0401b2f47500..f5812ca48bf2 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4212,6 +4212,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
 
 	switch (port->pdt) {
 	case DP_PEER_DEVICE_NONE:
+		break;
 	case DP_PEER_DEVICE_MST_BRANCHING:
 		if (!port->mcs)
 			ret = connector_status_connected;
-- 
2.30.0