[Why & How]
According to DP spec, broadcast message LCT equals to 1 and LCR equals
to 6. Current implementation is incorrect. Fix it.
In addition, revise a bit the hdr->rad handling to include broadcast
case.
Signed-off-by: Wayne Lin <Wayne.Lin@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/gpu/drm/drm_dp_mst_topology.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 17dbed0a9800..f11b3f718031 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2727,10 +2727,15 @@ static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
else
hdr->broadcast = 0;
hdr->path_msg = txmsg->path_msg;
- hdr->lct = mstb->lct;
- hdr->lcr = mstb->lct - 1;
- if (mstb->lct > 1)
- memcpy(hdr->rad, mstb->rad, mstb->lct / 2);
+ if (hdr->broadcast) {
+ hdr->lct = 1;
+ hdr->lcr = 6;
+ } else {
+ hdr->lct = mstb->lct;
+ hdr->lcr = mstb->lct - 1;
+ }
+
+ memcpy(hdr->rad, mstb->rad, hdr->lct / 2);
return 0;
}
--
2.17.1
