- 2'b11: count the events which sent to the uring_ext (MATA) channel;
- 2'b01: is the same as 2'b11;
- 2'b10: count the events which sent to the uring (non-MATA) channel;
- - 2'b00: default value, count the events which sent to the both uring and
- uring_ext channel;
+ - 2'b00: default value, count the events which sent to both uring and
+ uring_ext channels;
+6. ch: NoC PMU supports filtering the event counts of certain transaction
+channel with this option. The current supported channels are as follows:
+
+- 3'b010: Request channel
+- 3'b100: Snoop channel
+- 3'b110: Response channel
+- 3'b111: Data channel
+
+7. tt_en: NoC PMU supports counting only transactions that have tracetag set
+if this option is set. See the 2nd list for more information about tracetag.
+
+For HiSilicon uncore PMU v3 whose identifier is 0x40, some uncore PMUs are
+further divided into parts for finer granularity of tracing, each part has its
+own dedicated PMU, and all such PMUs together cover the monitoring job of events
+on particular uncore device. Such PMUs are described in sysfs with name format
+slightly changed::
+
+/sys/bus/event_source/devices/hisi_sccl{X}_<l3c{Y}_{Z}/ddrc{Y}_{Z}/noc{Y}_{Z}>
+
+Z is the sub-id, indicating different PMUs for part of hardware device.
+
+Usage of most PMUs with different sub-ids are identical. Specially, L3C PMU
+provides ``ext`` option to allow exploration of even finer granual statistics
+of L3C PMU. L3C PMU driver uses that as hint of termination when delivering
+perf command to hardware:
+
+- ext=0: Default, could be used with event names.
+- ext=1 and ext=2: Must be used with event codes, event names are not supported.
+
+An example of perf command could be::
+
+ $# perf stat -a -e hisi_sccl0_l3c1_0/rd_spipe/ sleep 5
+
+or::
+
+ $# perf stat -a -e hisi_sccl0_l3c1_0/event=0x1,ext=1/ sleep 5
+
+As above, ``hisi_sccl0_l3c1_0`` locates PMU of Super CPU CLuster 0, L3 cache 1
+pipe0.
+
+First command locates the first part of L3C since ``ext=0`` is implied by
+default. Second command issues the counting on another part of L3C with the
+event ``0x1``.
+
Users could configure IDs to count data come from specific CCL/ICL, by setting
srcid_cmd & srcid_msk, and data desitined for specific CCL/ICL by setting
tgtid_cmd & tgtid_msk. A set bit in srcid_msk/tgtid_msk means the PMU will not