On Mon, Feb 22, 2021 at 12:00:26PM +0800, Wayne Lin wrote:
> [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);
We should also do something about RAD no?
>
> --
> 2.17.1
>
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--
Ville Syrjälä
Intel
