[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@amd.com Cc: stable@vger.kernel.org --- 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; }