root@j721s2-evm:/opt/1323.test# devmem2 0x688040 w 0x80000001
/dev/mem opened.
Memory mapped at address 0xffff8a69c000.
Read at address  0x00688040 (0xffff8a69c040): 0x80000000
Write at address 0x00688040 (0xffff8a69c040): 0x80000001, readback 0x80000001
root@j721s2-evm:/opt/1323.test#
root@j721s2-evm:/opt/1323.test# ^C
root@j721s2-evm:/opt/1323.test# ^C
root@j721s2-evm:/opt/1323.test# ls
test.out
root@j721s2-evm:/opt/1323.test# ./test.out
======================cost:10007793===========
root@j721s2-evm:/opt/1323.test# k3conf dump clocks | grep -i a72
|     4     |     0    | DEV_A72SS0_ARM_CLK_CLK                                                            | CLK_STATE_READY     | 2000000000      |
|     4     |     1    | DEV_A72SS0_MSMC_CLK                                                               | CLK_STATE_READY     | 1000000000      |
|     4     |     2    | DEV_A72SS0_PLL_CTRL_CLK                                                           | CLK_STATE_READY     | 500000000       |
|     4     |     6    | DEV_A72SS0_A72_DIVH_CLK8_OBSCLK_OUT_CLK                                           | CLK_STATE_READY     | 0               |
|   202     |     0    | DEV_A72SS0_CORE0_ARM_CLK_CLK                                                      | CLK_STATE_READY     | 2000000000      |
|   203     |     0    | DEV_A72SS0_CORE1_ARM_CLK_CLK                                                      | CLK_STATE_READY     | 2000000000      |
root@j721s2-evm:/opt/1323.test# k3conf set clock 4 0 1200000000
|-------------------------------------------------------------------------------|
| VERSION INFO                                                                  |
|-------------------------------------------------------------------------------|
| K3CONF | (version 0.3-nogit built Thu Jul 25 14:13:02 UTC 2024)               |
| SoC    | J721S2 SR1.0                                                         |
| SYSFW  | ABI: 4.0 (firmware version 0x000b '11.0.9--v11.00.09+ (Fancy Rat))') |
|-------------------------------------------------------------------------------|

|----------------------------------------------------------------------------------------------------|
| Device ID | Clock ID | Clock Name                              | Status          | Clock Frequency |
|----------------------------------------------------------------------------------------------------|
|     4     |     0    | DEV_A72SS0_ARM_CLK_CLK                  | CLK_STATE_READY | 1200000000      |
|     4     |     1    | DEV_A72SS0_MSMC_CLK                     | CLK_STATE_READY | 1000000000      |
|     4     |     2    | DEV_A72SS0_PLL_CTRL_CLK                 | CLK_STATE_READY | 500000000       |
|     4     |     6    | DEV_A72SS0_A72_DIVH_CLK8_OBSCLK_OUT_CLK | CLK_STATE_READY | 0               |
|----------------------------------------------------------------------------------------------------|

root@j721s2-evm:/opt/1323.test# ./test.out
======================cost:16687739===========
root@j721s2-evm:/opt/1323.test# uname -a
Linux j721s2-evm 6.6.44-ti-gd41d875bdfc8-dirty #2 SMP PREEMPT Thu Jul 24 16:10:22 CDT 2025 aarch64 GNU/Linux
root@j721s2-evm:/opt/1323.test#