Re: [PATCH] drm: Update MST First Link Slot Information Based on Encoding Format

[Lyude Paul <lyude@redhat.com>]

[more snip]

On Fri, 2021-10-15 at 15:43 -0400, Bhawanpreet Lakha wrote:
> > 
> Thanks for the response,
> 
> That function is per port so not sure how that will work. Also we only 
> need to check this inside drm_dp_mst_atomic_check_vcpi_alloc_limit(), 
> which doesn't have a state.
> 
> We could add the slots(or some DP version indicator) inside the 
> drm_connector, and add a parameter to 
> drm_dp_mst_atomic_check_vcpi_alloc_limit(int slots)? and call it with 
> this info via drm_dp_mst_atomic_check() and then update the mgr->slot in 
> commit.

TBH - I think we can actually just get away with having all of this info in
drm_dp_mst_topology_state

> 
> 
> Bhawan
> 
> > >                  ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr-
> > > > mst_primary,
> > >                                                              mst_state);
> > >                  mutex_unlock(&mgr->lock);
> > > @@ -5527,11 +5543,16 @@ int drm_dp_mst_topology_mgr_init(struct
> > > drm_dp_mst_topology_mgr *mgr,
> > >          if (!mgr->proposed_vcpis)
> > >                  return -ENOMEM;
> > >          set_bit(0, &mgr->payload_mask);
> > > +       mgr->total_avail_slots = 63;
> > > +       mgr->start_slot = 1;
> > >   
> > >          mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
> > >          if (mst_state == NULL)
> > >                  return -ENOMEM;
> > >   
> > > +       mst_state->total_avail_slots = 63;
> > > +       mst_state->start_slot = 1;
> > > +
> > >          mst_state->mgr = mgr;
> > >          INIT_LIST_HEAD(&mst_state->vcpis);
> > >   
> > > diff --git a/include/drm/drm_dp_mst_helper.h
> > > b/include/drm/drm_dp_mst_helper.h
> > > index ddb9231d0309..f8152dfb34ed 100644
> > > --- a/include/drm/drm_dp_mst_helper.h
> > > +++ b/include/drm/drm_dp_mst_helper.h
> > > @@ -554,6 +554,8 @@ struct drm_dp_mst_topology_state {
> > >          struct drm_private_state base;
> > >          struct list_head vcpis;
> > >          struct drm_dp_mst_topology_mgr *mgr;
> > > +       u8 total_avail_slots;
> > > +       u8 start_slot;
> > >   };
> > >   
> > >   #define to_dp_mst_topology_mgr(x) container_of(x, struct
> > > drm_dp_mst_topology_mgr, base)
> > > @@ -661,6 +663,16 @@ struct drm_dp_mst_topology_mgr {
> > >           */
> > >          int pbn_div;
> > >   
> > > +       /**
> > > +        * @total_avail_slots: 63 for 8b/10b, 64 for 128/132b
> > > +        */
> > > +       u8 total_avail_slots;
> > > +
> > > +       /**
> > > +        * @start_slot: 1 for 8b/10b, 0 for 128/132b
> > > +        */
> > > +       u8 start_slot;
> > > +
> > >          /**
> > >           * @funcs: Atomic helper callbacks
> > >           */
> > > @@ -806,6 +818,7 @@ int drm_dp_mst_get_vcpi_slots(struct
> > > drm_dp_mst_topology_mgr *mgr, struct drm_dp
> > >   
> > >   void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
> > > struct drm_dp_mst_port *port);
> > >   
> > > +void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state
> > > *mst_state, uint8_t link_coding_cap);
> > >   
> > >   void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
> > >                                  struct drm_dp_mst_port *port);
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat