[PATCH v5 2/4] docs/perf: Add documentation for the Amlogic G12 DDR PMU

[Jiucheng Xu <jiucheng.xu@amlogic.com>]

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>
Reported-by: kernel test robot <lkp@intel.com>
---
Changes v5 -> v4:
  - Fix building warning

Changes v3 -> v4:
  - No change

Changes v2 -> v3:
  - Rename doc name from aml-ddr-pmu.rst to meson-ddr-pmu.rst

Changes v1 -> v2:
  - Nothing was changed
---
 Documentation/admin-guide/perf/index.rst      |  1 +
 .../admin-guide/perf/meson-ddr-pmu.rst        | 70 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 3 files changed, 72 insertions(+)
 create mode 100644 Documentation/admin-guide/perf/meson-ddr-pmu.rst

diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst
index 69b23f087c05..997a28e156c1 100644
--- a/Documentation/admin-guide/perf/index.rst
+++ b/Documentation/admin-guide/perf/index.rst
@@ -17,3 +17,4 @@ Performance monitor support
    xgene-pmu
    arm_dsu_pmu
    thunderx2-pmu
+   meson-ddr-pmu
diff --git a/Documentation/admin-guide/perf/meson-ddr-pmu.rst b/Documentation/admin-guide/perf/meson-ddr-pmu.rst
new file mode 100644
index 000000000000..c0ef7b71b975
--- /dev/null
+++ b/Documentation/admin-guide/perf/meson-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:
+
++ meson_ddr_bw/total_rw_bytes/
++ meson_ddr_bw/chan_1_rw_bytes/
++ meson_ddr_bw/chan_2_rw_bytes/
++ meson_ddr_bw/chan_3_rw_bytes/
++ meson_ddr_bw/chan_4_rw_bytes/
+
+meson_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 meson_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 meson_ddr_bw/chan_1_rw_bytes,arm=1/ -I 1000 sleep 10
+      perf stat -a -e meson_ddr_bw/chan_2_rw_bytes,gpu=1/ -I 1000 sleep 10
+      perf stat -a -e meson_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 ac8a98dfbacc..8ee68e699e6d 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/meson-ddr-pmu.rst
 F:	drivers/perf/amlogic/
 F:	include/soc/amlogic/
 
-- 
2.25.1