On Fri, Nov 16, 2018 at 07:21:15PM -0500, Lyude Paul wrote:
> Some hardware (nvidia hardware in particular) needs to be notified of
> the exact VCPI and payload settings that the topology manager decided on
> for each mstb port. Since there isn't currently any way to get this
> information without going through port (which drivers are very much not
> supposed to do by themselves, ever), let's add one.
>
> Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 56 +++++++++++++++++++++++++++
> include/drm/drm_dp_mst_helper.h | 5 ++-
> 2 files changed, 60 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 529414556962..4336d17ce904 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -1982,6 +1982,62 @@ int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr)
> }
> EXPORT_SYMBOL(drm_dp_update_payload_part2);
>
> +/**
> + * drm_dp_get_payload_info() - Retrieve payload/vcpi information for the given
> + * @port
> + * @mgr: manager to use
> + * @port: the port to get the relevant payload information for
> + * @vcpi_out: where to copy the port's VCPI information to
> + * @payload_out: where to copy the port's payload information to
> + *
> + * Searches the current payloads for @mgr and finds the relevant payload and
> + * VCPI information that was programmed by the topology mgr, then copies it
> + * into @vcpi_out and @payload_out. Drivers which need to know this
> + * information must use this helper as opposed to checking @port themselves,
> + * as this helper will ensure the port reference is still valid and grab the
> + * appropriate locks in @mgr.
> + *
> + * Returns:
> + * 0 on success, negative error code if the port is no longer valid or a
> + * programmed payload could not be found for @port.
> + */
> +int drm_dp_get_payload_info(struct drm_dp_mst_topology_mgr *mgr,
> + struct drm_dp_mst_port *port,
> + struct drm_dp_vcpi *vcpi_out,
> + struct drm_dp_payload *payload_out)
> +{
> + struct drm_dp_payload *payload = NULL;
> + int i;
> + int ret = 0;
> +
> + port = drm_dp_get_validated_port_ref(mgr, port);
> + if (!port)
> + return -EINVAL;
This is the part that I mean in our other/irc discussions. The
dp_get_validated_port here could fail when it's going to surprise the
driver. With the dp_port_malloc_get stuff we could instead just grab a
port_malloc_kref when storing the port in mgr->payload, which would
guarantee that the port based lookup below still works.
> +
> + mutex_lock(&mgr->payload_lock);
> + /* Figure out which of the payloads belongs to this port */
> + for (i = 0; i < mgr->max_payloads; i++) {
> + if (mgr->payloads[i].vcpi == port->vcpi.vcpi) {
Or maybe even rework the lookup here to use the port pointer (as an
abstract key) instead of port->vcpi.vcpi. With port_malloc_kref we could
guarantee that it keeps working, even after the port has been destroyed.
And (without checking) I think that's needed anyway to clean up the
payload update hacks in the connector destroy work ...
-Daniel
> + payload = &mgr->payloads[i];
> + break;
> + }
> + }
> +
> + if (!payload) {
> + DRM_DEBUG_KMS("Failed to find payload for port %p\n", port);
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + *payload_out = *payload;
> + *vcpi_out = port->vcpi;
> +out:
> + mutex_unlock(&mgr->payload_lock);
> + drm_dp_put_port(port);
> + return ret;
> +}
> +EXPORT_SYMBOL(drm_dp_get_payload_info);
> +
> #if 0 /* unused as of yet */
> static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
> struct drm_dp_mst_port *port,
> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> index 59f005b419cf..9cc93ea60e7e 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -592,7 +592,10 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
> struct drm_dp_mst_port *port, int pbn, int slots);
>
> int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
> -
> +int drm_dp_get_payload_info(struct drm_dp_mst_topology_mgr *mgr,
> + struct drm_dp_mst_port *port,
> + struct drm_dp_vcpi *vcpi_out,
> + struct drm_dp_payload *payload_out);
>
> void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
>
> --
> 2.19.1
>
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> Nouveau@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/nouveau
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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