1.. SPDX-License-Identifier: GPL-2.0
2
3===========================================================
4Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)
5===========================================================
6
7The Amlogic Meson G12 SoC contains a bandwidth monitor inside DRAM controller.
8The monitor includes 4 channels. Each channel can count the request accessing
9DRAM. The channel can count up to 3 AXI port simultaneously. It can be helpful
10to show if the performance bottleneck is on DDR bandwidth.
11
12Currently, this driver supports the following 5 perf events:
13
14+ meson_ddr_bw/total_rw_bytes/
15+ meson_ddr_bw/chan_1_rw_bytes/
16+ meson_ddr_bw/chan_2_rw_bytes/
17+ meson_ddr_bw/chan_3_rw_bytes/
18+ meson_ddr_bw/chan_4_rw_bytes/
19
20meson_ddr_bw/chan_{1,2,3,4}_rw_bytes/ events are channel-specific events.
21Each channel support filtering, which can let the channel to monitor
22individual IP module in SoC.
23
24Below are DDR access request event filter keywords:
25
26+ arm             - from CPU
27+ vpu_read1       - from OSD + VPP read
28+ gpu             - from 3D GPU
29+ pcie            - from PCIe controller
30+ hdcp            - from HDCP controller
31+ hevc_front      - from HEVC codec front end
32+ usb3_0          - from USB3.0 controller
33+ hevc_back       - from HEVC codec back end
34+ h265enc         - from HEVC encoder
35+ vpu_read2       - from DI read
36+ vpu_write1      - from VDIN write
37+ vpu_write2      - from di write
38+ vdec            - from legacy codec video decoder
39+ hcodec          - from H264 encoder
40+ ge2d            - from ge2d
41+ spicc1          - from SPI controller 1
42+ usb0            - from USB2.0 controller 0
43+ dma             - from system DMA controller 1
44+ arb0            - from arb0
45+ sd_emmc_b       - from SD eMMC b controller
46+ usb1            - from USB2.0 controller 1
47+ audio           - from Audio module
48+ sd_emmc_c       - from SD eMMC c controller
49+ spicc2          - from SPI controller 2
50+ ethernet        - from Ethernet controller
51
52
53Examples:
54
55  + Show the total DDR bandwidth per seconds:
56
57    .. code-block:: bash
58
59       perf stat -a -e meson_ddr_bw/total_rw_bytes/ -I 1000 sleep 10
60
61
62  + Show individual DDR bandwidth from CPU and GPU respectively, as well as
63    sum of them:
64
65    .. code-block:: bash
66
67       perf stat -a -e meson_ddr_bw/chan_1_rw_bytes,arm=1/ -I 1000 sleep 10
68       perf stat -a -e meson_ddr_bw/chan_2_rw_bytes,gpu=1/ -I 1000 sleep 10
69       perf stat -a -e meson_ddr_bw/chan_3_rw_bytes,arm=1,gpu=1/ -I 1000 sleep 10
70
71