[PATCH 1/3] drm/display/dp_mst: Fix down/up message handling after sink disconnect

[Lyude Paul]

For the whole series:

Reviewed-by: Lyude Paul <lyude at redhat.com>

Thanks!

On Wed, 2022-12-14 at 20:42 +0200, Imre Deak wrote:
> If the sink gets disconnected during receiving a multi-packet DP MST AUX
> down-reply/up-request sideband message, the state keeping track of which
> packets have been received already is not reset. This results in a failed
> sanity check for the subsequent message packet received after a sink is
> reconnected (due to the pending message not yet completed with an
> end-of-message-transfer packet), indicated by the
> 
> "sideband msg set header failed"
> 
> error.
> 
> Fix the above by resetting the up/down message reception state after a
> disconnect event.
> 
> Cc: Lyude Paul <lyude at redhat.com>
> Cc: <stable at vger.kernel.org> # v3.17+
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/display/drm_dp_mst_topology.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> index 51a46689cda70..90819fff2c9ba 100644
> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> @@ -3641,6 +3641,9 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
>  		drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
>  		ret = 0;
>  		mgr->payload_id_table_cleared = false;
> +
> +		memset(&mgr->down_rep_recv, 0, sizeof(mgr->down_rep_recv));
> +		memset(&mgr->up_req_recv, 0, sizeof(mgr->up_req_recv));
>  	}
>  
>  out_unlock:

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat