|
On 1/27/2024 12:06 PM, Arun R Murthy wrote: > With DP2.1, multistream packetization and the underneth MST protocol > will be required for SST. So check for MSTM_CAP to see if MST is really > required and skip the MSTM_CTRL write so that we ensure that only the > underneth protocol and the multistream packetization will be enabled and > sink will not be confused by a corresponding dpcd write. > > Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx> > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 26 +++++++++++-------- > 1 file changed, 15 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > index 8ca01a6bf645..22d81732a978 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -3666,10 +3666,11 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms > mgr->mst_primary = mstb; > drm_dp_mst_topology_get_mstb(mgr->mst_primary); > > - ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, > - DP_MST_EN | > - DP_UP_REQ_EN | > - DP_UPSTREAM_IS_SRC); > + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) > + ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, > + DP_MST_EN | > + DP_UP_REQ_EN | > + DP_UPSTREAM_IS_SRC); > if (ret < 0) > goto out_unlock; > > @@ -3684,7 +3685,8 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms > mstb = mgr->mst_primary; > mgr->mst_primary = NULL; > /* this can fail if the device is gone */ > - drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); > + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) > + drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); > ret = 0; > mgr->payload_id_table_cleared = false; > > @@ -3724,8 +3726,9 @@ drm_dp_mst_topology_mgr_invalidate_mstb(struct drm_dp_mst_branch *mstb) > void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr) > { > mutex_lock(&mgr->lock); > - drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, > - DP_MST_EN | DP_UPSTREAM_IS_SRC); > + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) > + drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, > + DP_MST_EN | DP_UPSTREAM_IS_SRC); > mutex_unlock(&mgr->lock); > flush_work(&mgr->up_req_work); > flush_work(&mgr->work); > @@ -3773,10 +3776,11 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr, > goto out_fail; > } > > - ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, > - DP_MST_EN | > - DP_UP_REQ_EN | > - DP_UPSTREAM_IS_SRC); > + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) > + ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, This did not compile in Chrome dev environemnt due to uninitialized variable ret. > + DP_MST_EN | > + DP_UP_REQ_EN | > + DP_UPSTREAM_IS_SRC); > if (ret < 0) { > drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n"); > goto out_fail; Tested-by: Charlton Lin <charlton.lin@xxxxxxxxx> Regards, Charlton Lin |
