@@ -2092,7 +2092,10 @@ static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
}
}
- return ret;
+ if (ret < 16 && ret > 0)
+ return -EPROTO;
+
+ return ret == 16 ? 0 : ret;
}
static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
@@ -2907,8 +2910,14 @@ static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
drm_dp_dump_link_address(reply);
ret = drm_dp_check_mstb_guid(mstb, reply->guid);
- if (ret)
+ if (ret) {
+ char buf[64];
+
+ drm_dp_mst_rad_to_str(mstb->rad, mstb->lct, buf, sizeof(buf));
+ DRM_ERROR("GUID check on %s failed: %d\n",
+ buf, ret);
goto out;
+ }
for (i = 0; i < reply->nports; i++) {
port_mask |= BIT(reply->ports[i].port_number);
We actually expect this to return a 0 on success, or negative error code on failure. In order to do that, we check whether or not we managed to write the whole GUID and then return 0 if so, otherwise return a negative error code. Also, let's add an error message here so it's a little more obvious when this fails in the middle of a link address probe. This should fix issues with certain MST hubs seemingly stopping for no reason in the middle of the link address probe process. Fixes: cb897542c6d2 ("drm/dp_mst: Fix W=1 warnings") Cc: Benjamin Gaignard <benjamin.gaignard@st.com> Cc: Sean Paul <sean@poorly.run> Cc: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Lyude Paul <lyude@redhat.com> --- drivers/gpu/drm/drm_dp_mst_topology.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)