Add explanation for DDR_CAP_AXI_ID_PORT_CHANNEL_FILTER quirk.
Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
---
Changes since v2:
- no changes
---
Documentation/admin-guide/perf/imx-ddr.rst | 45 ++++++++++++++++++----
1 file changed, 37 insertions(+), 8 deletions(-)
diff --git a/Documentation/admin-guide/perf/imx-ddr.rst b/Documentation/admin-guide/perf/imx-ddr.rst
index 90926d0fb8ec..77418ae5a290 100644
--- a/Documentation/admin-guide/perf/imx-ddr.rst
+++ b/Documentation/admin-guide/perf/imx-ddr.rst
@@ -13,8 +13,8 @@ is one register for each counter. Counter 0 is special in that it always counts
interrupt is raised. If any other counter overflows, it continues counting, and
no interrupt is raised.
-The "format" directory describes format of the config (event ID) and config1
-(AXI filtering) fields of the perf_event_attr structure, see /sys/bus/event_source/
+The "format" directory describes format of the config (event ID) and config1/2
+(AXI filter setting) fields of the perf_event_attr structure, see /sys/bus/event_source/
devices/imx8_ddr0/format/. The "events" directory describes the events types
hardware supported that can be used with perf tool, see /sys/bus/event_source/
devices/imx8_ddr0/events/. The "caps" directory describes filter features implemented
@@ -28,12 +28,11 @@ in DDR PMU, see /sys/bus/events_source/devices/imx8_ddr0/caps/.
AXI filtering is only used by CSV modes 0x41 (axid-read) and 0x42 (axid-write)
to count reading or writing matches filter setting. Filter setting is various
from different DRAM controller implementations, which is distinguished by quirks
-in the driver. You also can dump info from userspace, filter in "caps" directory
-indicates whether PMU supports AXI ID filter or not; enhanced_filter indicates
-whether PMU supports enhanced AXI ID filter or not. Value 0 for un-supported, and
-value 1 for supported.
+in the driver. You also can dump info from userspace, "caps" directory show the
+type of AXI filter (filter, enhanced_filter and super_filter). Value 0 for
+un-supported, and value 1 for supported.
-* With DDR_CAP_AXI_ID_FILTER quirk(filter: 1, enhanced_filter: 0).
+* With DDR_CAP_AXI_ID_FILTER quirk(filter: 1, enhanced_filter: 0, super_filter: 0).
Filter is defined with two configuration parts:
--AXI_ID defines AxID matching value.
--AXI_MASKING defines which bits of AxID are meaningful for the matching.
@@ -65,7 +64,37 @@ value 1 for supported.
perf stat -a -e imx8_ddr0/axid-read,axi_id=0x12/ cmd, which will monitor ARID=0x12
-* With DDR_CAP_AXI_ID_FILTER_ENHANCED quirk(filter: 1, enhanced_filter: 1).
+* With DDR_CAP_AXI_ID_FILTER_ENHANCED quirk(filter: 1, enhanced_filter: 1, super_filter: 0).
This is an extension to the DDR_CAP_AXI_ID_FILTER quirk which permits
counting the number of bytes (as opposed to the number of bursts) from DDR
read and write transactions concurrently with another set of data counters.
+
+* With DDR_CAP_AXI_ID_PORT_CHANNEL_FILTER quirk(filter: 0, enhanced_filter: 0, super_filter: 1).
+ There is a limitation in previous AXI filter, it cannot filter different IDs
+ at the same time as the filter is shared between counters. This quirk is the
+ extension of AXI ID filter. One improvement is that counter 1-3 has their own
+ filter, means that it supports concurrently filter various IDs. Another
+ improvement is that counter 1-3 supports AXI PORT and CHANNEL selection. Support
+ selecting address channel or data channel.
+
+ Filter is defined with 2 configuration registers per counter 1-3.
+ --Counter N MASK COMP register - including AXI_ID and AXI_MASKING.
+ --Counter N MUX CNTL register - including AXI CHANNEL and AXI PORT.
+
+ - 0: address channel
+ - 1: data channel
+
+ PMU in DDR subsystem, only one single port0 exists, so axi_port is reserved
+ which should be 0.
+
+ .. code-block:: bash
+
+ perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD,axi_channel=0xH/ cmd
+ perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD,axi_channel=0xH/ cmd
+
+ .. note::
+
+ axi_channel is inverted in userspace, and it will be reverted in driver
+ automatically. So that users do not need specify axi_channel if want to
+ monitor data channel from DDR transactions, since data channel is more
+ meaningful.
--
2.34.1
