On Tue, 2019-12-03 at 09:35 -0500, mikita.lipski@xxxxxxx wrote:
> From: Mikita Lipski <mikita.lipski@xxxxxxx>
>
> [why]
> Whenever a connector on an MST network is changed or
> undergoes a modeset, the DSC configs for each stream on that
> topology will be recalculated. This can change their required
> bandwidth, requiring a full reprogramming, as though a modeset
> was performed, even if that stream did not change timing.
>
> [how]
> Adding helper to trigger modesets on MST DSC connectors
> by setting mode_changed flag on CRTCs in the same topology
> as affected connector
>
> v2: use drm_dp_mst_dsc_aux_for_port function to verify
> if the port is DSC capable
>
> Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> Cc: Lyude Paul <lyude@xxxxxxxxxx>
> Signed-off-by: Mikita Lipski <mikita.lipski@xxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 62 +++++++++++++++++++++++++++
> include/drm/drm_dp_mst_helper.h | 2 +
> 2 files changed, 64 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 76bcbb4cd8b4..fb3710b727cc 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -4802,6 +4802,68 @@ drm_dp_mst_atomic_check_topology_state(struct
> drm_dp_mst_topology_mgr *mgr,
> return 0;
> }
>
> +/**
> + * drm_dp_mst_add_affected_dsc_crtcs
> + * @state: Pointer to the new &struct drm_dp_mst_topology_state
> + * @port: Pointer tothe port of connector with new state
> + *
> + * Whenever there is a change in mst topology
> + * DSC configuration would have to be recalculated
> + * therefore we need to trigger modeset on all affected
> + * CRTCs in that topology
> + *
> + * See also:
> + * drm_dp_mst_atomic_enable_dsc()
> + */
> +int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state,
> struct drm_dp_mst_topology_mgr *mgr)
> +{
> + struct drm_dp_mst_topology_state *mst_state;
> + struct drm_dp_vcpi_allocation *pos;
> + struct drm_connector *connector;
> + struct drm_connector_state *conn_state;
> + struct drm_crtc *crtc;
> + struct drm_crtc_state *crtc_state;
> +
> + if (!mgr) {
> + DRM_DEBUG_ATOMIC("[MST MGR:%p] Passed Topology Manager pointer
> is pointing to NULL\n", mgr);
> + return -EINVAL;
> + }
I'd get rid of this check, we'll notice pretty easily if it's NULL :P
> +
> + mst_state = drm_atomic_get_mst_topology_state(state, mgr);
Forgot to check IS_ERR(mst_state) here
> +
> + list_for_each_entry(pos, &mst_state->vcpis, next) {
> +
> + connector = pos->port->connector;
> +
> + if (!connector)
> + return -EINVAL;
> +
> + conn_state = drm_atomic_get_connector_state(state, connector);
> +
> + if (IS_ERR(conn_state))
> + return PTR_ERR(conn_state);
> +
> + crtc = conn_state->crtc;
> +
> + if (!crtc)
> + return -EINVAL;
This seems like something that would be an error from a driver using the API
incorrectly, maybe this should be something like
if (WARN_ON(!crtc))
return -EINVAL;
> +
> + if (!drm_dp_mst_dsc_aux_for_port(pos->port))
> + continue;
> +
> + crtc_state = drm_atomic_get_crtc_state(mst_state->base.state,
> crtc);
> +
> + if (IS_ERR(crtc_state))
> + return PTR_ERR(crtc_state);
> +
> + DRM_DEBUG_ATOMIC("[MST MGR:%p] Setting mode_changed flag on
> CRTC %p\n", mgr, crtc);
This can be wrapped a bit more to fit in 80 chars
> +
> + crtc_state->mode_changed = true;
Nitpick here: I usually try to group assignments and conditional checks on
those assignments unless it makes it more difficult to read, like:
ret = cool_function();
if (ret)
return ret;
But not too big of a deal either way. Won't hold back review
> + }
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_mst_add_affected_dsc_crtcs);
> +
> /**
> * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
> * @state: Pointer to the new drm_atomic_state
> diff --git a/include/drm/drm_dp_mst_helper.h
> b/include/drm/drm_dp_mst_helper.h
> index 2919d9776af3..10e9c7049061 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -779,6 +779,8 @@ int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state
> *state,
> struct drm_dp_mst_port *port,
> int pbn, int pbn_div,
> bool enable);
> +int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr);
I'd add a __must_check attribute here. With the more important changes
addressed here:
Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
> int __must_check
> drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
> struct drm_dp_mst_topology_mgr *mgr,
--
Cheers,
Lyude Paul
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