[PATCH 3.19.y-ckt 073/210] drm/dp/mst: fix in RAD element access

[Kamal Mostafa]

3.19.8-ckt14 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Mykola Lysenko <Mykola.Lysenko at amd.com>

commit 7a11a334aa6af4c65c6a0d81b60c97fc18673532 upstream.

This is needed to receive correct port
number from RAD, so MSTB could be found

Acked-by: Dave Airlie <airlied at gmail.com>
Signed-off-by: Mykola Lysenko <Mykola.Lysenko at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 4710d2f..85aebb2 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1035,7 +1035,7 @@ static void build_mst_prop_path(struct drm_dp_mst_port *port,
 	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
 	for (i = 0; i < (mstb->lct - 1); i++) {
 		int shift = (i % 2) ? 0 : 4;
-		int port_num = mstb->rad[i / 2] >> shift;
+		int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
 		snprintf(temp, sizeof(temp), "-%d", port_num);
 		strlcat(proppath, temp, proppath_size);
 	}
@@ -1185,7 +1185,7 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
 
 	for (i = 0; i < lct - 1; i++) {
 		int shift = (i % 2) ? 0 : 4;
-		int port_num = rad[i / 2] >> shift;
+		int port_num = (rad[i / 2] >> shift) & 0xf;
 
 		list_for_each_entry(port, &mstb->ports, next) {
 			if (port->port_num == port_num) {
-- 
1.9.1