[PATCH 4.2.y-ckt 085/268] drm/dp/mst: fix in MSTB RAD initialization

[Kamal Mostafa]

4.2.8-ckt3 -stable review patch.  If anyone has any objections, please let me know.

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

From: Mykola Lysenko <Mykola.Lysenko@xxxxxxx>

commit 75af4c8c4c0f60d7ad135419805798f144e9baf9 upstream.

This fix is needed to support more then two
branch displays, so RAD address consist at
least of 2 elements

Acked-by: Dave Airlie <airlied@xxxxxxxxx>
Signed-off-by: Mykola Lysenko <Mykola.Lysenko@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index d620fe9..74c0c08 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -973,17 +973,17 @@ static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u
 static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
 				 u8 *rad)
 {
-	int lct = port->parent->lct;
+	int parent_lct = port->parent->lct;
 	int shift = 4;
-	int idx = lct / 2;
-	if (lct > 1) {
-		memcpy(rad, port->parent->rad, idx);
-		shift = (lct % 2) ? 4 : 0;
+	int idx = (parent_lct - 1) / 2;
+	if (parent_lct > 1) {
+		memcpy(rad, port->parent->rad, idx + 1);
+		shift = (parent_lct % 2) ? 4 : 0;
 	} else
 		rad[0] = 0;
 
 	rad[idx] |= port->port_num << shift;
-	return lct + 1;
+	return parent_lct + 1;
 }
 
 /*
-- 
1.9.1