[PATCH] drm/dp_mst: Don't drop NAKs for down responses

From: Lyude Paul
Date: Fri Apr 03 2020 - 16:03:50 EST


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@xxxxxxxxxx>
Fixes: fbc821c4a506 ("drm/mst: Support simultaneous down replies")
Cc: Wayne Lin <Wayne.Lin@xxxxxxx>
Cc: Wayne Lin <waynelin@xxxxxxx>
Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
---
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;
}

memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
--
2.25.1