[PATCH 2/4] docs/perf: Add documentation for the Amlogic G12 DDR PMU

[Jiucheng Xu]

Add a user guide to show how to use DDR PMU to
monitor DDR bandwidth on Amlogic G12 SoC

Signed-off-by: Jiucheng Xu <jiucheng.xu at amlogic.com>
---
 .../admin-guide/perf/aml-ddr-pmu.rst          | 70 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 71 insertions(+)
 create mode 100644 Documentation/admin-guide/perf/aml-ddr-pmu.rst

diff --git a/Documentation/admin-guide/perf/aml-ddr-pmu.rst b/Documentation/admin-guide/perf/aml-ddr-pmu.rst
new file mode 100644
index 000000000000..a441eeb7d968
--- /dev/null
+++ b/Documentation/admin-guide/perf/aml-ddr-pmu.rst
@@ -0,0 +1,70 @@
+.. SPDX-License-Identifier: GPL-2.0
+===========================================================
+Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)
+===========================================================
+
+There is a bandwidth monitor inside the DRAM contorller. The monitor include
+4 channels which can count the read/write request of accessing DRAM individually.
+It can be helpful to show if the performance bottleneck is on DDR bandwidth.
+
+Currently, this driver supports the following 5 Perf events:
+
+aml_ddr_bw/total_rw_bytes/
+aml_ddr_bw/chan_1_rw_bytes/
+aml_ddr_bw/chan_2_rw_bytes/
+aml_ddr_bw/chan_3_rw_bytes/
+aml_ddr_bw/chan_4_rw_bytes/
+
+aml_ddr_bw/chan_{1,2,3,4}_rw_bytes/ events are the channel related events.
+Each channel support using keywords as filter, which can let the channel
+to monitor the individual IP module in SoC.
+
+The following keywords are the filter:
+
+arm             - DDR access request from CPU
+vpu_read1       - DDR access request from OSD + VPP read
+gpu             - DDR access request from 3D GPU
+pcie            - DDR access request from PCIe controller
+hdcp            - DDR access request from HDCP controller
+hevc_front      - DDR access request from HEVC codec front end
+usb3_0          - DDR access request from USB3.0 controller
+hevc_back       - DDR access request from HEVC codec back end
+h265enc         - DDR access request from HEVC encoder
+vpu_read2       - DDR access request from DI read
+vpu_write1      - DDR access request from VDIN write
+vpu_write2      - DDR access request from di write
+vdec            - DDR access request from legacy codec video decoder
+hcodec          - DDR access request from H264 encoder
+ge2d            - DDR access request from ge2d
+spicc1          - DDR access request from SPI controller 1
+usb0            - DDR access request from USB2.0 controller 0
+dma             - DDR access request from system DMA controller 1
+arb0            - DDR access request from arb0
+sd_emmc_b       - DDR access request from SD eMMC b controller
+usb1            - DDR access request from USB2.0 controller 1
+audio           - DDR access request from Audio module
+sd_emmc_c       - DDR access request from SD eMMC c controller
+spicc2          - DDR access request from SPI controller 2
+ethernet        - DDR access request from Ethernet controller
+
+The following command is to show the total DDR bandwidth:
+
+    .. code-block::bash
+
+        perf stat -a -e aml_ddr_bw/total_rw_bytes/ -I 1000 sleep 10
+
+This command will print the total DDR bandwidth per second.
+
+The following commands are to show how to use filter parameters:
+
+    .. code-block::bash
+
+        perf stat -a -e aml_ddr_bw/chan_1_rw_bytes,arm=1/ -I 1000 sleep 10
+        perf stat -a -e aml_ddr_bw/chan_2_rw_bytes,gpu=1/ -I 1000 sleep 10
+        perf stat -a -e aml_ddr_bw/chan_3_rw_bytes,arm=1,gpu=1/ -I 1000 sleep 10
+
+The 1st command show how to use channel 1 to monitor the DDR bandwidth from ARM.
+The 2nd command show using channel 2 to get the DDR bandwidth of GPU.
+The 3rd command show using channel 3 to monitor the sum of ARM and GPU.
+
+
diff --git a/MAINTAINERS b/MAINTAINERS
index cb6ee59a4f44..fd2a56a339b4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1054,6 +1054,7 @@ AMLOGIC DDR PMU DRIVER
 M:	Jiucheng Xu <jiucheng.xu at amlogic.com>
 S:	Supported
 W:	http://www.amlogic.com
+F:	Documentation/admin-guide/perf/aml-ddr-pmu.rst
 F:	drivers/perf/amlogic/
 F:	include/soc/amlogic/
 
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2.25.1