On Tue, 14 Jun 2022, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote: > On Tue, 14 Jun 2022, Imre Deak <imre.deak@xxxxxxxxx> wrote: >> The WD22TB4 Thunderbolt dock at least will revert its DP_MAX_LINK_RATE >> from HBR3 to HBR2 after system suspend/resume if the DP_DP13_DPCD_REV >> registers are not read subsequently also as required. > > Does it actually change the behaviour depending on whether the dpcd is > read or not, or is this just about the resume path overwriting mgr->dpcd > with stuff from DP_DPCD_REV? > > drm_dp_mst_topology_mgr_set_mst() does use drm_dp_read_dpcd_caps() for > reading the caps, which would normally set mgr->dpcd from > DP_DP13_DPCD_REV. Oh, Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx> on the changes, I'm just wondering about the statement in the commit message. > > BR, > Jani. > >> >> Fix this by reading DP_DP13_DPCD_REV registers as well, matching what is >> done during connector detection. While at it also fix up the same call >> in drm_dp_mst_dump_topology(). >> >> Cc: Lyude Paul <lyude@xxxxxxxxxx> >> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5292 >> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> >> --- >> drivers/gpu/drm/display/drm_dp_mst_topology.c | 7 ++----- >> 1 file changed, 2 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c >> index 67b3b9697da7f..18f2b6075b780 100644 >> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c >> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c >> @@ -3860,9 +3860,7 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr, >> if (!mgr->mst_primary) >> goto out_fail; >> >> - ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, >> - DP_RECEIVER_CAP_SIZE); >> - if (ret != DP_RECEIVER_CAP_SIZE) { >> + if (drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd) < 0) { >> drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n"); >> goto out_fail; >> } >> @@ -4911,8 +4909,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m, >> u8 buf[DP_PAYLOAD_TABLE_SIZE]; >> int ret; >> >> - ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE); >> - if (ret) { >> + if (drm_dp_read_dpcd_caps(mgr->aux, buf) < 0) { >> seq_printf(m, "dpcd read failed\n"); >> goto out; >> } -- Jani Nikula, Intel Open Source Graphics Center
