drm/i915/dp: Add support to notify MST connectors to retry modesets

On shared (Thunderbolt) links with DP tunnels, the modeset may need to
be retried on all connectors on the link due to a link BW limitation
arising only after the atomic check phase. To support this add a helper
function queuing a work to retry the modeset on a given port's connector
and at the same time any MST connector with streams through the same
port. A follow-up change enabling the DP tunnel Bandwidth Allocation
Mode will take this into use.

v2:
- Send the uevent only to enabled MST connectors. (Jouni)

Cc: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240220211841.448846-5-imre.deak@intel.com

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

@@ -8086,8 +8086,9 @@ void intel_hpd_poll_fini(struct drm_i915_private *i915)
 	/* Kill all the work that may have been queued by hpd. */
 	drm_connector_list_iter_begin(&i915->drm, &conn_iter);
 	for_each_intel_connector_iter(connector, &conn_iter) {
-		if (connector->modeset_retry_work.func)
-			cancel_work_sync(&connector->modeset_retry_work);
+		if (connector->modeset_retry_work.func &&
+		    cancel_work_sync(&connector->modeset_retry_work))
+			drm_connector_put(&connector->base);
 		if (connector->hdcp.shim) {
 			cancel_delayed_work_sync(&connector->hdcp.check_work);
 			cancel_work_sync(&connector->hdcp.prop_work);

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

@@ -2842,6 +2842,40 @@ intel_dp_audio_compute_config(struct intel_encoder *encoder,
 					intel_dp_is_uhbr(pipe_config);
 }
 
+void intel_dp_queue_modeset_retry_work(struct intel_connector *connector)
+{
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+
+	drm_connector_get(&connector->base);
+	if (!queue_work(i915->unordered_wq, &connector->modeset_retry_work))
+		drm_connector_put(&connector->base);
+}
+
+void
+intel_dp_queue_modeset_retry_for_link(struct intel_atomic_state *state,
+				      struct intel_encoder *encoder,
+				      const struct intel_crtc_state *crtc_state)
+{
+	struct intel_connector *connector;
+	struct intel_digital_connector_state *conn_state;
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	int i;
+
+	if (!intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST)) {
+		intel_dp_queue_modeset_retry_work(intel_dp->attached_connector);
+
+		return;
+	}
+
+	for_each_new_intel_connector_in_state(state, connector, conn_state, i) {
+		if (!conn_state->base.crtc)
+			continue;
+
+		if (connector->mst_port == intel_dp)
+			intel_dp_queue_modeset_retry_work(connector);
+	}
+}
+
 int
 intel_dp_compute_config(struct intel_encoder *encoder,
 			struct intel_crtc_state *pipe_config,
@@ -6441,6 +6475,14 @@ static void intel_dp_modeset_retry_work_fn(struct work_struct *work)
 	mutex_unlock(&connector->dev->mode_config.mutex);
 	/* Send Hotplug uevent so userspace can reprobe */
 	drm_kms_helper_connector_hotplug_event(connector);
+
+	drm_connector_put(connector);
+}
+
+void intel_dp_init_modeset_retry_work(struct intel_connector *connector)
+{
+	INIT_WORK(&connector->modeset_retry_work,
+		  intel_dp_modeset_retry_work_fn);
 }
 
 bool
@@ -6457,8 +6499,7 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
 	int type;
 
 	/* Initialize the work for modeset in case of link train failure */
-	INIT_WORK(&intel_connector->modeset_retry_work,
-		  intel_dp_modeset_retry_work_fn);
+	intel_dp_init_modeset_retry_work(intel_connector);
 
 	if (drm_WARN(dev, dig_port->max_lanes < 1,
 		     "Not enough lanes (%d) for DP on [ENCODER:%d:%s]\n",

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

@@ -43,6 +43,12 @@ void intel_dp_adjust_compliance_config(struct intel_dp *intel_dp,
 bool intel_dp_limited_color_range(const struct intel_crtc_state *crtc_state,
 				  const struct drm_connector_state *conn_state);
 int intel_dp_min_bpp(enum intel_output_format output_format);
+void intel_dp_init_modeset_retry_work(struct intel_connector *connector);
+void intel_dp_queue_modeset_retry_work(struct intel_connector *connector);
+void
+intel_dp_queue_modeset_retry_for_link(struct intel_atomic_state *state,
+				      struct intel_encoder *encoder,
+				      const struct intel_crtc_state *crtc_state);
 bool intel_dp_init_connector(struct intel_digital_port *dig_port,
 			     struct intel_connector *intel_connector);
 void intel_dp_set_link_params(struct intel_dp *intel_dp,

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

@@ -1075,7 +1075,6 @@ static void intel_dp_schedule_fallback_link_training(struct intel_dp *intel_dp,
 						     const struct intel_crtc_state *crtc_state)
 {
 	struct intel_connector *intel_connector = intel_dp->attached_connector;
-	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 
 	if (!intel_digital_port_connected(&dp_to_dig_port(intel_dp)->base)) {
 		lt_dbg(intel_dp, DP_PHY_DPRX, "Link Training failed on disconnected sink.\n");
@@ -1093,7 +1092,7 @@ static void intel_dp_schedule_fallback_link_training(struct intel_dp *intel_dp,
 	}
 
 	/* Schedule a Hotplug Uevent to userspace to start modeset */
-	queue_work(i915->unordered_wq, &intel_connector->modeset_retry_work);
+	intel_dp_queue_modeset_retry_work(intel_connector);
 }
 
 /* Perform the link training on all LTTPRs and the DPRX on a link. */

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

@@ -1546,6 +1546,8 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
 	intel_connector->port = port;
 	drm_dp_mst_get_port_malloc(port);
 
+	intel_dp_init_modeset_retry_work(intel_connector);
+
 	intel_connector->dp.dsc_decompression_aux = drm_dp_mst_dsc_aux_for_port(port);
 	intel_dp_mst_read_decompression_port_dsc_caps(intel_dp, intel_connector);
 	intel_connector->dp.dsc_hblank_expansion_quirk =