Re: [PATCH] drm/dp_mst: clear time slots for ports invalid

[Lyude Paul <lyude@redhat.com>]

Hi! I will try to review this patch today, must have gotten lost in the noise

On Fri, 2019-12-20 at 01:46 +0000, Lin, Wayne wrote:
> [AMD Official Use Only - Internal Distribution Only]
> 
> Pinged.
> Hi, can someone help to review please.
> 
> Thanks a lot.
> 
> Regards,
> Wayne
> 
> ________________________________________
> From: Wayne Lin <Wayne.Lin@amd.com>
> Sent: Friday, December 6, 2019 16:39
> To: dri-devel@lists.freedesktop.org; amd-gfx@lists.freedesktop.org
> Cc: Kazlauskas, Nicholas; Wentland, Harry; Zuo, Jerry; lyude@redhat.com; 
> stable@vger.kernel.org; Lin, Wayne
> Subject: [PATCH] drm/dp_mst: clear time slots for ports invalid
> 
> [Why]
> When change the connection status in a MST topology, mst device
> which detect the event will send out CONNECTION_STATUS_NOTIFY messgae.
> 
> e.g. src-mst-mst-sst => src-mst (unplug) mst-sst
> 
> Currently, under the above case of unplugging device, ports which have
> been allocated payloads and are no longer in the topology still occupy
> time slots and recorded in proposed_vcpi[] of topology manager.
> 
> If we don't clean up the proposed_vcpi[], when code flow goes to try to
> update payload table by calling drm_dp_update_payload_part1(), we will
> fail at checking port validation due to there are ports with proposed
> time slots but no longer in the mst topology. As the result of that, we
> will also stop updating the DPCD payload table of down stream port.
> 
> [How]
> While handling the CONNECTION_STATUS_NOTIFY message, add a detection to
> see if the event indicates that a device is unplugged to an output port.
> If the detection is true, then iterrate over all proposed_vcpi[] to
> see whether a port of the proposed_vcpi[] is still in the topology or
> not. If the port is invalid, set its num_slots to 0.
> 
> Thereafter, when try to update payload table by calling
> drm_dp_update_payload_part1(), we can successfully update the DPCD
> payload table of down stream port and clear the proposed_vcpi[] to NULL.
> 
> Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 5306c47dc820..2e236b6275c4 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2318,7 +2318,7 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch
> *mstb,
>  {
>         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
>         struct drm_dp_mst_port *port;
> -       int old_ddps, ret;
> +       int old_ddps, old_input, ret, i;
>         u8 new_pdt;
>         bool dowork = false, create_connector = false;
> 
> @@ -2349,6 +2349,7 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch
> *mstb,
>         }
> 
>         old_ddps = port->ddps;
> +       old_input = port->input;
>         port->input = conn_stat->input_port;
>         port->mcs = conn_stat->message_capability_status;
>         port->ldps = conn_stat->legacy_device_plug_status;
> @@ -2373,6 +2374,27 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch
> *mstb,
>                 dowork = false;
>         }
> 
> +       if (!old_input && old_ddps != port->ddps && !port->ddps) {
> +               for (i = 0; i < mgr->max_payloads; i++) {
> +                       struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
> +                       struct drm_dp_mst_port *port_validated;
> +
> +                       if (vcpi) {
> +                               port_validated =
> +                                       container_of(vcpi, struct
> drm_dp_mst_port, vcpi);
> +                               port_validated =
> +                                       drm_dp_mst_topology_get_port_validat
> ed(mgr, port_validated);
> +                               if (!port_validated) {
> +                                       mutex_lock(&mgr->payload_lock);
> +                                       vcpi->num_slots = 0;
> +                                       mutex_unlock(&mgr->payload_lock);
> +                               } else {
> +                                       drm_dp_mst_topology_put_port(port_va
> lidated);
> +                               }
> +                       }
> +               }
> +       }
> +
>         if (port->connector)
>                 drm_modeset_unlock(&mgr->base.lock);
>         else if (create_connector)
> --
> 2.17.1
> 
-- 
Cheers,
	Lyude Paul

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