v4.19.13 snapshot.
diff --git a/Documentation/ABI/testing/sysfs-class-stm_source b/Documentation/ABI/testing/sysfs-class-stm_source
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index 0000000..57b8dd3
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+What: /sys/class/stm_source/<stm_source>/stm_source_link
+Date: June 2015
+KernelVersion: 4.3
+Contact: Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:
+ stm_source device linkage to stm device, where its tracing data
+ is directed. Reads return an existing connection or "<none>" if
+ this stm_source is not connected to any stm device yet.
+ Write an existing (registered) stm device's name here to
+ connect that device. If a device is already connected to this
+ stm_source, it will first be disconnected.