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

Jiucheng Xu
2022-07-12T06:52:18Z

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@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@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