[Why & How]
According to DP spec, broadcast message LCT equals to 1 and LCR equals
to 6. Current implementation is incorrect. Fix it.
Signed-off-by: Wayne Lin <Wayne.Lin@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 17dbed0a9800..713ef3b42054 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2727,8 +2727,14 @@ 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 (hdr->broadcast) {
+ hdr->lct = 1;
+ hdr->lcr = 6;
+ } else {
+ hdr->lct = mstb->lct;
+ hdr->lcr = mstb->lct - 1;
+ }
+
if (mstb->lct > 1)
memcpy(hdr->rad, mstb->rad, mstb->lct / 2);
--
2.17.1
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