drm/i915/dp: Fix connector DSC HW state readout

The DSC HW state of DP connectors is read out during driver loading and
system resume in intel_modeset_update_connector_atomic_state(). This
function is called for all connectors though and so the state of DSI
connectors will also get updated incorrectly, triggering a WARN there
wrt. the DSC decompression AUX device.

Fix the above by moving the DSC state readout to a new DP connector
specific sync_state() hook. This is anyway the logical place to update
the connector object's state vs. the connector's atomic state.

Fixes: b2608c6 ("drm/i915/dp_mst: Enable MST DSC decompression for all streams")
Reported-and-tested-by: Drew Davenport <ddavenport@chromium.org>
Closes: https://lore.kernel.org/all/Zb0q8IDVXS0HxJyj@chromium.org
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240205132631.1588577-1-imre.deak@intel.com

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

@@ -613,6 +613,13 @@ struct intel_connector {
 	 * and active (i.e. dpms ON state). */
 	bool (*get_hw_state)(struct intel_connector *);
 
+	/*
+	 * Optional hook called during init/resume to sync any state
+	 * stored in the connector (eg. DSC state) wrt. the HW state.
+	 */
+	void (*sync_state)(struct intel_connector *connector,
+			   const struct intel_crtc_state *crtc_state);
+
 	/* Panel info for eDP and LVDS */
 	struct intel_panel panel;
 

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

@@ -5942,6 +5942,19 @@ intel_dp_connector_unregister(struct drm_connector *connector)
 	intel_connector_unregister(connector);
 }
 
+void intel_dp_connector_sync_state(struct intel_connector *connector,
+				   const struct intel_crtc_state *crtc_state)
+{
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+
+	if (crtc_state && crtc_state->dsc.compression_enable) {
+		drm_WARN_ON(&i915->drm, !connector->dp.dsc_decompression_aux);
+		connector->dp.dsc_decompression_enabled = true;
+	} else {
+		connector->dp.dsc_decompression_enabled = false;
+	}
+}
+
 void intel_dp_encoder_flush_work(struct drm_encoder *encoder)
 {
 	struct intel_digital_port *dig_port = enc_to_dig_port(to_intel_encoder(encoder));

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

@@ -51,6 +51,8 @@ intel_dp_queue_modeset_retry_for_link(struct intel_atomic_state *state,
 				      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_connector_sync_state(struct intel_connector *connector,
+				   const struct intel_crtc_state *crtc_state);
 void intel_dp_set_link_params(struct intel_dp *intel_dp,
 			      int link_rate, int lane_count);
 int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,

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

@@ -1554,6 +1554,7 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
 		return NULL;
 
 	intel_connector->get_hw_state = intel_dp_mst_get_hw_state;
+	intel_connector->sync_state = intel_dp_connector_sync_state;
 	intel_connector->mst_port = intel_dp;
 	intel_connector->port = port;
 	drm_dp_mst_get_port_malloc(port);

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

@@ -318,12 +318,6 @@ static void intel_modeset_update_connector_atomic_state(struct drm_i915_private
 			const struct intel_crtc_state *crtc_state =
 				to_intel_crtc_state(crtc->base.state);
 
-			if (crtc_state->dsc.compression_enable) {
-				drm_WARN_ON(&i915->drm, !connector->dp.dsc_decompression_aux);
-				connector->dp.dsc_decompression_enabled = true;
-			} else {
-				connector->dp.dsc_decompression_enabled = false;
-			}
 			conn_state->max_bpc = (crtc_state->pipe_bpp ?: 24) / 3;
 		}
 	}
@@ -775,8 +769,9 @@ static void intel_modeset_readout_hw_state(struct drm_i915_private *i915)
 
 	drm_connector_list_iter_begin(&i915->drm, &conn_iter);
 	for_each_intel_connector_iter(connector, &conn_iter) {
+		struct intel_crtc_state *crtc_state = NULL;
+
 		if (connector->get_hw_state(connector)) {
-			struct intel_crtc_state *crtc_state;
 			struct intel_crtc *crtc;
 
 			connector->base.dpms = DRM_MODE_DPMS_ON;
@@ -802,6 +797,10 @@ static void intel_modeset_readout_hw_state(struct drm_i915_private *i915)
 			connector->base.dpms = DRM_MODE_DPMS_OFF;
 			connector->base.encoder = NULL;
 		}
+
+		if (connector->sync_state)
+			connector->sync_state(connector, crtc_state);
+
 		drm_dbg_kms(&i915->drm,
 			    "[CONNECTOR:%d:%s] hw state readout: %s\n",
 			    connector->base.base.id, connector->base.name,