drm/i915/mst: split out a helper for figuring out the TU

Extract intel_dp_mtp_tu_compute_config() for figuring out the TU. Move
the link configuration and mst state access to the callers. This will be
easier to adapt to 128b/132b SST.

v2: Don't add SST stuff here yet

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c3ea8370c9bd3cdc579159e68a63f4ed2fadc66a.1735912293.git.jani.nikula@intel.com

Author: jnikula

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

@@ -209,40 +209,32 @@ static int intel_dp_mst_dsc_get_slice_count(const struct intel_connector *connec
 					    num_joined_pipes);
 }
 
-static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
-					      struct intel_crtc_state *crtc_state,
-					      int max_bpp, int min_bpp,
-					      struct link_config_limits *limits,
-					      struct drm_connector_state *conn_state,
-					      int step, bool dsc)
+int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
+				   struct intel_crtc_state *crtc_state,
+				   int max_bpp, int min_bpp,
+				   struct drm_connector_state *conn_state,
+				   int step, bool dsc)
 {
 	struct intel_display *display = to_intel_display(intel_dp);
 	struct drm_atomic_state *state = crtc_state->uapi.state;
-	struct drm_dp_mst_topology_state *mst_state;
 	struct intel_connector *connector =
 		to_intel_connector(conn_state->connector);
 	const struct drm_display_mode *adjusted_mode =
 		&crtc_state->hw.adjusted_mode;
+	fixed20_12 pbn_div;
 	int bpp, slots = -EINVAL;
 	int dsc_slice_count = 0;
 	int max_dpt_bpp;
 
-	mst_state = drm_atomic_get_mst_topology_state(state, &intel_dp->mst_mgr);
-	if (IS_ERR(mst_state))
-		return PTR_ERR(mst_state);
-
-	crtc_state->lane_count = limits->max_lane_count;
-	crtc_state->port_clock = limits->max_rate;
-
 	if (dsc) {
 		if (!intel_dp_supports_fec(intel_dp, connector, crtc_state))
 			return -EINVAL;
 
 		crtc_state->fec_enable = !intel_dp_is_uhbr(crtc_state);
 	}
 
-	mst_state->pbn_div = drm_dp_get_vc_payload_bw(crtc_state->port_clock,
-						      crtc_state->lane_count);
+	pbn_div = drm_dp_get_vc_payload_bw(crtc_state->port_clock,
+					   crtc_state->lane_count);
 
 	max_dpt_bpp = intel_dp_mst_max_dpt_bpp(crtc_state, dsc);
 	if (max_bpp > max_dpt_bpp) {
@@ -302,7 +294,7 @@ static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
 		pbn.full = dfixed_const(intel_dp_mst_calc_pbn(adjusted_mode->crtc_clock,
 							      link_bpp_x16,
 							      remote_bw_overhead));
-		remote_tu = DIV_ROUND_UP(pbn.full, mst_state->pbn_div.full);
+		remote_tu = DIV_ROUND_UP(pbn.full, pbn_div.full);
 
 		/*
 		 * Aligning the TUs ensures that symbols consisting of multiple
@@ -320,7 +312,7 @@ static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
 		 * allocated for the whole path and the TUs allocated for the
 		 * first branch device's link also applies here.
 		 */
-		pbn.full = remote_tu * mst_state->pbn_div.full;
+		pbn.full = remote_tu * pbn_div.full;
 
 		drm_WARN_ON(display->drm, remote_tu < crtc_state->dp_m_n.tu);
 		crtc_state->dp_m_n.tu = remote_tu;
@@ -355,6 +347,31 @@ static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
 	return 0;
 }
 
+static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
+					      struct intel_crtc_state *crtc_state,
+					      int max_bpp, int min_bpp,
+					      struct link_config_limits *limits,
+					      struct drm_connector_state *conn_state,
+					      int step, bool dsc)
+{
+	struct drm_atomic_state *state = crtc_state->uapi.state;
+	struct drm_dp_mst_topology_state *mst_state;
+
+	mst_state = drm_atomic_get_mst_topology_state(state, &intel_dp->mst_mgr);
+	if (IS_ERR(mst_state))
+		return PTR_ERR(mst_state);
+
+	crtc_state->lane_count = limits->max_lane_count;
+	crtc_state->port_clock = limits->max_rate;
+
+	mst_state->pbn_div = drm_dp_get_vc_payload_bw(crtc_state->port_clock,
+						      crtc_state->lane_count);
+
+	return intel_dp_mtp_tu_compute_config(intel_dp, crtc_state,
+					      max_bpp, min_bpp,
+					      conn_state, step, dsc);
+}
+
 static int mst_stream_compute_link_config(struct intel_dp *intel_dp,
 					  struct intel_crtc_state *crtc_state,
 					  struct drm_connector_state *conn_state,

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

@@ -8,6 +8,7 @@
 
 #include <linux/types.h>
 
+struct drm_connector_state;
 struct intel_atomic_state;
 struct intel_crtc;
 struct intel_crtc_state;
@@ -30,4 +31,10 @@ bool intel_dp_mst_crtc_needs_modeset(struct intel_atomic_state *state,
 void intel_dp_mst_prepare_probe(struct intel_dp *intel_dp);
 bool intel_dp_mst_verify_dpcd_state(struct intel_dp *intel_dp);
 
+int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
+				   struct intel_crtc_state *crtc_state,
+				   int max_bpp, int min_bpp,
+				   struct drm_connector_state *conn_state,
+				   int step, bool dsc);
+
 #endif /* __INTEL_DP_MST_H__ */