We should drop this and the versions for all of the other kernel versions. This patch later got reverted in a86675968e2300fb567994459da3dbc4cd1b322a in drm-misc/drm-misc-next, and then replaced with a proper fix in 8732fe46b20c951493bfc4dba0ad08efdf41de81 On Thu, 2020-02-13 at 07:20 -0800, Greg Kroah-Hartman wrote: > From: Wayne Lin <Wayne.Lin@xxxxxxx> > > [ Upstream commit 64e62bdf04ab8529f45ed0a85122c703035dec3a ] > > [Why] > > This patch is trying to address the issue observed when hotplug DP > daisy chain monitors. > > e.g. > src-mstb-mstb-sst -> src (unplug) mstb-mstb-sst -> src-mstb-mstb-sst > (plug in again) > > Once unplug a DP MST capable device, driver will call > drm_dp_mst_topology_mgr_set_mst() to disable MST. In this function, > it cleans data of topology manager while disabling mst_state. However, > it doesn't clean up the proposed_vcpis of topology manager. > If proposed_vcpi is not reset, once plug in MST daisy chain monitors > later, code will fail at checking port validation while trying to > allocate payloads. > > When MST capable device is plugged in again and try to allocate > payloads by calling drm_dp_update_payload_part1(), this > function will iterate over all proposed virtual channels to see if > any proposed VCPI's num_slots is greater than 0. If any proposed > VCPI's num_slots is greater than 0 and the port which the > specific virtual channel directed to is not in the topology, code then > fails at the port validation. Since there are stale VCPI allocations > from the previous topology enablement in proposed_vcpi[], code will fail > at port validation and reurn EINVAL. > > [How] > > Clean up the data of stale proposed_vcpi[] and reset mgr->proposed_vcpis > to NULL while disabling mst in drm_dp_mst_topology_mgr_set_mst(). > > Changes since v1: > *Add on more details in commit message to describe the issue which the > patch is trying to fix > > Signed-off-by: Wayne Lin <Wayne.Lin@xxxxxxx> > [added cc to stable] > Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx> > Link: > https://patchwork.freedesktop.org/patch/msgid/20191205090043.7580-1-Wayne.Lin@xxxxxxx > Cc: <stable@xxxxxxxxxxxxxxx> # v3.17+ > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c > b/drivers/gpu/drm/drm_dp_mst_topology.c > index 17aedaaf364c1..8b1d497b7f99f 100644 > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > @@ -2042,6 +2042,7 @@ static bool drm_dp_get_vc_payload_bw(int dp_link_bw, > int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, > bool mst_state) > { > int ret = 0; > + int i = 0; > struct drm_dp_mst_branch *mstb = NULL; > > mutex_lock(&mgr->lock); > @@ -2106,10 +2107,21 @@ int drm_dp_mst_topology_mgr_set_mst(struct > drm_dp_mst_topology_mgr *mgr, bool ms > /* this can fail if the device is gone */ > drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); > ret = 0; > + mutex_lock(&mgr->payload_lock); > memset(mgr->payloads, 0, mgr->max_payloads * sizeof(struct > drm_dp_payload)); > mgr->payload_mask = 0; > set_bit(0, &mgr->payload_mask); > + for (i = 0; i < mgr->max_payloads; i++) { > + struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i]; > + > + if (vcpi) { > + vcpi->vcpi = 0; > + vcpi->num_slots = 0; > + } > + mgr->proposed_vcpis[i] = NULL; > + } > mgr->vcpi_mask = 0; > + mutex_unlock(&mgr->payload_lock); > } > > out_unlock: -- Cheers, Lyude Paul (she/her) Associate Software Engineer at Red Hat
