drm/amd/display: Add sink/link debug logs

Add some extra logs to better help triage blackscreen issues.

* Dump all the links to see if they have sinks associated.
* Print the edid manufacturer & product id associated with a stream that
  was just created.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3392,6 +3392,67 @@ static void apply_delay_after_dpcd_poweroff(struct amdgpu_device *adev,
 	}
 }
 
+/**
+ * amdgpu_dm_dump_links_and_sinks - Debug dump of all DC links and their sinks
+ * @adev: amdgpu device pointer
+ *
+ * Iterates through all DC links and dumps information about local and remote
+ * (MST) sinks. Should be called after connector detection is complete to see
+ * the final state of all links.
+ */
+static void amdgpu_dm_dump_links_and_sinks(struct amdgpu_device *adev)
+{
+	struct dc *dc = adev->dm.dc;
+	struct drm_device *dev = adev_to_drm(adev);
+	int li;
+
+	if (!dc)
+		return;
+
+	for (li = 0; li < dc->link_count; li++) {
+		struct dc_link *l = dc->links[li];
+		const char *name = NULL;
+		int rs;
+
+		if (!l)
+			continue;
+		if (l->local_sink && l->local_sink->edid_caps.display_name[0])
+			name = l->local_sink->edid_caps.display_name;
+		else
+			name = "n/a";
+
+		drm_dbg_kms(dev,
+			"LINK_DUMP[%d]: local_sink=%p type=%d sink_signal=%d sink_count=%u edid_name=%s mst_capable=%d mst_alloc_streams=%d\n",
+			li,
+			l->local_sink,
+			l->type,
+			l->local_sink ? l->local_sink->sink_signal : SIGNAL_TYPE_NONE,
+			l->sink_count,
+			name,
+			l->dpcd_caps.is_mst_capable,
+			l->mst_stream_alloc_table.stream_count);
+
+		/* Dump remote (MST) sinks if any */
+		for (rs = 0; rs < l->sink_count; rs++) {
+			struct dc_sink *rsink = l->remote_sinks[rs];
+			const char *rname = NULL;
+
+			if (!rsink)
+				continue;
+			if (rsink->edid_caps.display_name[0])
+				rname = rsink->edid_caps.display_name;
+			else
+				rname = "n/a";
+			drm_dbg_kms(dev,
+				"  REMOTE_SINK[%d:%d]: sink=%p signal=%d edid_name=%s\n",
+				li, rs,
+				rsink,
+				rsink->sink_signal,
+				rname);
+		}
+	}
+}
+
 static int dm_resume(struct amdgpu_ip_block *ip_block)
 {
 	struct amdgpu_device *adev = ip_block->adev;
@@ -3576,6 +3637,12 @@ static int dm_resume(struct amdgpu_ip_block *ip_block)
 	}
 	drm_connector_list_iter_end(&iter);
 
+	/* Debug dump: list all DC links and their associated sinks after detection
+	 * is complete for all connectors. This provides a comprehensive view of the
+	 * final state without repeating the dump for each connector.
+	 */
+	amdgpu_dm_dump_links_and_sinks(adev);
+
 	amdgpu_dm_irq_resume_late(adev);
 
 	amdgpu_dm_smu_write_watermarks_table(adev);
@@ -5407,6 +5474,12 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 		amdgpu_set_panel_orientation(&aconnector->base);
 	}
 
+	/* Debug dump: list all DC links and their associated sinks after detection
+	 * is complete for all connectors. This provides a comprehensive view of the
+	 * final state without repeating the dump for each connector.
+	 */
+	amdgpu_dm_dump_links_and_sinks(adev);
+
 	/* Software is initialized. Now we can register interrupt handlers. */
 	switch (adev->asic_type) {
 #if defined(CONFIG_DRM_AMD_DC_SI)

drivers/gpu/drm/amd/display/dc/core/dc_stream.c

@@ -879,9 +879,11 @@ void dc_stream_log(const struct dc *dc, const struct dc_stream_state *stream)
 			stream->sink->sink_signal != SIGNAL_TYPE_NONE) {
 
 			DC_LOG_DC(
-					"\tdispname: %s signal: %x\n",
+					"\tsignal: %x dispname: %s manufacturer_id: 0x%x product_id: 0x%x\n",
+					stream->signal,
 					stream->sink->edid_caps.display_name,
-					stream->signal);
+					stream->sink->edid_caps.manufacturer_id,
+					stream->sink->edid_caps.product_id);
 		}
 	}
 }