On Fri, Apr 3, 2020 at 4:03 PM Lyude Paul lyude@redhat.com wrote:

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

Thank you for fixing this

Reviewed-by: Sean Paul sean@poorly.run

---

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