Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Lyude Paul <lyude@redhat.com>
To:     dri-devel@lists.freedesktop.org
Cc:     Wayne Lin <Wayne.Lin@amd.com>, Wayne Lin <waynelin@amd.com>,
        Sean Paul <seanpaul@chromium.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, linux-kernel@vger.kernel.org
Subject: [PATCH] drm/dp_mst: Don't drop NAKs for down responses
Date:   Fri,  3 Apr 2020 16:03:25 -0400
Message-Id: <20200403200325.885628-1-lyude@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

It looks like that when we introduced the ability to handle multiple
down requests at once, we accidentally started dropping NAK replies -
causing sideband messages which got NAK'd to seemingly timeout and cause
all sorts of weirdness.

So, fix this by making sure we don't return from
drm_dp_mst_handle_down_rep() early, but instead treat NAKs like any
other message.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: fbc821c4a506 ("drm/mst: Support simultaneous down replies")
Cc: Wayne Lin <Wayne.Lin@amd.com>
Cc: Wayne Lin <waynelin@amd.com>
Cc: Sean Paul <seanpaul@chromium.org>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_=
dp_mst_topology.c
index 10d0315af513..5449ada3e019 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3813,7 +3813,6 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp=
_mst_topology_mgr *mgr)
 			      txmsg->reply.u.nak.reason,
 			      drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
 			      txmsg->reply.u.nak.nak_data);
-		goto out_clear_reply;
 	}
=20
 	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
--=20
2.25.1