diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt
index 5f0922613f1a..a977339fbe0a 100644
--- a/Documentation/networking/timestamping.txt
+++ b/Documentation/networking/timestamping.txt
@@ -359,6 +359,13 @@ the requested fine-grained filtering for incoming packets is not
 supported, the driver may time stamp more than just the requested types
 of packets.
 
+Drivers are free to use a more permissive configuration than the requested
+configuration. It is expected that drivers should only implement directly the
+most generic mode that can be supported. For example if the hardware can
+support HWTSTAMP_FILTER_V2_EVENT, then it should generally always upscale
+HWTSTAMP_FILTER_V2_L2_SYNC_MESSAGE, and so forth, as HWTSTAMP_FILTER_V2_EVENT
+is more generic (and more useful to applications).
+
 A driver which supports hardware time stamping shall update the struct
 with the actual, possibly more permissive configuration. If the
 requested packets cannot be time stamped, then nothing should be
diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index cd67aec187d9..cd1629170103 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -1093,6 +1093,11 @@ struct ethtool_sfeatures {
  * the 'hwtstamp_tx_types' and 'hwtstamp_rx_filters' enumeration values,
  * respectively.  For example, if the device supports HWTSTAMP_TX_ON,
  * then (1 << HWTSTAMP_TX_ON) in 'tx_types' will be set.
+ *
+ * Drivers should only report the filters they actually support without
+ * upscaling in the SIOCSHWTSTAMP ioctl. If the SIOCSHWSTAMP request for
+ * HWTSTAMP_FILTER_V1_SYNC is supported by HWTSTAMP_FILTER_V1_EVENT, then the
+ * driver should only report HWTSTAMP_FILTER_V1_EVENT in this op.
  */
 struct ethtool_ts_info {
 	__u32	cmd;