drm/display/dp_mst: Call them time slots, not VCPI slots

VCPI is only sort of the correct term here, originally the majority of this
code simply referred to timeslots vaguely as "slots" - and since I started
working on it and adding atomic functionality, the name "VCPI slots" has
been used to represent time slots.

Now that we actually have consistent access to the DisplayPort spec thanks
to VESA, I now know this isn't actually the proper term - as the
specification refers to these as time slots.

Since we're trying to make this code as easy to figure out as possible,
let's take this opportunity to correct this nomenclature and call them by
their proper name - timeslots. Likewise, we rename various functions
appropriately, along with replacing references in the kernel documentation
and various debugging messages.

It's important to note that this patch series leaves the legacy MST code
untouched for the most part, which is fine since we'll be removing it soon
anyhow. There should be no functional changes in this series.

v2:
* Add note that Wayne Lin from AMD suggested regarding slots being between
  the source DP Tx and the immediate downstream DP Rx
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Wayne Lin <Wayne.Lin@amd.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Fangzhi Zuo <Jerry.Zuo@amd.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sean Paul <sean@poorly.run>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220817193847.557945-5-lyude@redhat.com

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -6401,7 +6401,7 @@ static int dm_encoder_helper_atomic_check(struct drm_encoder *encoder,
 		clock = adjusted_mode->clock;
 		dm_new_connector_state->pbn = drm_dp_calc_pbn_mode(clock, bpp, false);
 	}
-	dm_new_connector_state->vcpi_slots = drm_dp_atomic_find_vcpi_slots(state,
+	dm_new_connector_state->vcpi_slots = drm_dp_atomic_find_time_slots(state,
 									   mst_mgr,
 									   mst_port,
 									   dm_new_connector_state->pbn,

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

@@ -472,7 +472,7 @@ static int dm_dp_mst_atomic_check(struct drm_connector *connector,
 			return 0;
 		}
 
-	return drm_dp_atomic_release_vcpi_slots(state,
+	return drm_dp_atomic_release_time_slots(state,
 						mst_mgr,
 						mst_port);
 }
@@ -785,7 +785,7 @@ static bool increase_dsc_bpp(struct drm_atomic_state *state,
 
 		if (initial_slack[next_index] > fair_pbn_alloc) {
 			vars[next_index].pbn += fair_pbn_alloc;
-			if (drm_dp_atomic_find_vcpi_slots(state,
+			if (drm_dp_atomic_find_time_slots(state,
 							  params[next_index].port->mgr,
 							  params[next_index].port,
 							  vars[next_index].pbn,
@@ -795,7 +795,7 @@ static bool increase_dsc_bpp(struct drm_atomic_state *state,
 				vars[next_index].bpp_x16 = bpp_x16_from_pbn(params[next_index], vars[next_index].pbn);
 			} else {
 				vars[next_index].pbn -= fair_pbn_alloc;
-				if (drm_dp_atomic_find_vcpi_slots(state,
+				if (drm_dp_atomic_find_time_slots(state,
 								  params[next_index].port->mgr,
 								  params[next_index].port,
 								  vars[next_index].pbn,
@@ -804,7 +804,7 @@ static bool increase_dsc_bpp(struct drm_atomic_state *state,
 			}
 		} else {
 			vars[next_index].pbn += initial_slack[next_index];
-			if (drm_dp_atomic_find_vcpi_slots(state,
+			if (drm_dp_atomic_find_time_slots(state,
 							  params[next_index].port->mgr,
 							  params[next_index].port,
 							  vars[next_index].pbn,
@@ -814,7 +814,7 @@ static bool increase_dsc_bpp(struct drm_atomic_state *state,
 				vars[next_index].bpp_x16 = params[next_index].bw_range.max_target_bpp_x16;
 			} else {
 				vars[next_index].pbn -= initial_slack[next_index];
-				if (drm_dp_atomic_find_vcpi_slots(state,
+				if (drm_dp_atomic_find_time_slots(state,
 								  params[next_index].port->mgr,
 								  params[next_index].port,
 								  vars[next_index].pbn,
@@ -872,7 +872,7 @@ static bool try_disable_dsc(struct drm_atomic_state *state,
 			break;
 
 		vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.stream_kbps);
-		if (drm_dp_atomic_find_vcpi_slots(state,
+		if (drm_dp_atomic_find_time_slots(state,
 						  params[next_index].port->mgr,
 						  params[next_index].port,
 						  vars[next_index].pbn,
@@ -884,7 +884,7 @@ static bool try_disable_dsc(struct drm_atomic_state *state,
 			vars[next_index].bpp_x16 = 0;
 		} else {
 			vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.max_kbps);
-			if (drm_dp_atomic_find_vcpi_slots(state,
+			if (drm_dp_atomic_find_time_slots(state,
 							  params[next_index].port->mgr,
 							  params[next_index].port,
 							  vars[next_index].pbn,
@@ -971,11 +971,11 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
 		vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps);
 		vars[i + k].dsc_enabled = false;
 		vars[i + k].bpp_x16 = 0;
-		if (drm_dp_atomic_find_vcpi_slots(state,
-						 params[i].port->mgr,
-						 params[i].port,
-						 vars[i + k].pbn,
-						 dm_mst_get_pbn_divider(dc_link)) < 0)
+		if (drm_dp_atomic_find_time_slots(state,
+						  params[i].port->mgr,
+						  params[i].port,
+						  vars[i + k].pbn,
+						  dm_mst_get_pbn_divider(dc_link)) < 0)
 			return false;
 	}
 	if (!drm_dp_mst_atomic_check(state) && !debugfs_overwrite) {
@@ -989,7 +989,7 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
 			vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.min_kbps);
 			vars[i + k].dsc_enabled = true;
 			vars[i + k].bpp_x16 = params[i].bw_range.min_target_bpp_x16;
-			if (drm_dp_atomic_find_vcpi_slots(state,
+			if (drm_dp_atomic_find_time_slots(state,
 							  params[i].port->mgr,
 							  params[i].port,
 							  vars[i + k].pbn,
@@ -999,7 +999,7 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
 			vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps);
 			vars[i + k].dsc_enabled = false;
 			vars[i + k].bpp_x16 = 0;
-			if (drm_dp_atomic_find_vcpi_slots(state,
+			if (drm_dp_atomic_find_time_slots(state,
 							  params[i].port->mgr,
 							  params[i].port,
 							  vars[i + k].pbn,

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -70,7 +70,7 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
 						       crtc_state->pipe_bpp,
 						       false);
 
-		slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr,
+		slots = drm_dp_atomic_find_time_slots(state, &intel_dp->mst_mgr,
 						      connector->port,
 						      crtc_state->pbn,
 						      drm_dp_get_vc_payload_bw(&intel_dp->mst_mgr,
@@ -344,8 +344,7 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
 	}
 
 	mgr = &enc_to_mst(to_intel_encoder(old_conn_state->best_encoder))->primary->dp.mst_mgr;
-	ret = drm_dp_atomic_release_vcpi_slots(&state->base, mgr,
-					       intel_connector->port);
+	ret = drm_dp_atomic_release_time_slots(&state->base, mgr, intel_connector->port);
 
 	return ret;
 }

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -1065,7 +1065,7 @@ nv50_msto_atomic_check(struct drm_encoder *encoder,
 						    false);
 	}
 
-	slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, mstc->port,
+	slots = drm_dp_atomic_find_time_slots(state, &mstm->mgr, mstc->port,
 					      asyh->dp.pbn, 0);
 	if (slots < 0)
 		return slots;
@@ -1277,7 +1277,7 @@ nv50_mstc_atomic_check(struct drm_connector *connector,
 			return 0;
 	}
 
-	return drm_dp_atomic_release_vcpi_slots(state, mgr, mstc->port);
+	return drm_dp_atomic_release_time_slots(state, mgr, mstc->port);
 }
 
 static int

include/drm/display/drm_dp_mst_helper.h

@@ -544,7 +544,13 @@ struct drm_dp_payload {
 
 struct drm_dp_mst_atomic_payload {
 	struct drm_dp_mst_port *port;
-	int vcpi;
+
+	/**
+	 * @time_slots:
+	 * The number of timeslots allocated to this payload from the source DP Tx to
+	 * the immediate downstream DP Rx
+	 */
+	int time_slots;
 	int pbn;
 	bool dsc_enabled;
 	struct list_head next;
@@ -846,7 +852,7 @@ void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
 struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
 								    struct drm_dp_mst_topology_mgr *mgr);
 int __must_check
-drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
+drm_dp_atomic_find_time_slots(struct drm_atomic_state *state,
 			      struct drm_dp_mst_topology_mgr *mgr,
 			      struct drm_dp_mst_port *port, int pbn,
 			      int pbn_div);
@@ -858,7 +864,7 @@ int __must_check
 drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state,
 				  struct drm_dp_mst_topology_mgr *mgr);
 int __must_check
-drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
+drm_dp_atomic_release_time_slots(struct drm_atomic_state *state,
 				 struct drm_dp_mst_topology_mgr *mgr,
 				 struct drm_dp_mst_port *port);
 int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,