CAM2_MCLK on TX2 r28.1 clock rate

Hi all:
We are using the CAM2_MCLK(E7) as the mclk for the sensor. I need to config the mclk to 24MHz.

root@tegra-ubuntu:/home/nvidia# cat /sys/kernel/debug/clk/extperiph3/
clk_accuracy           clk_notifier_count     clk_prepare_count
clk_enable_count       clk_phase              clk_rate
clk_flags              clk_possible_parents   frequency_stats_table
root@tegra-ubuntu:/home/nvidia# cat /sys/kernel/debug/clk/extperiph3/clk_rate 
19200000                                                                       t
    extperiph3                                              0            0    19200000    24000000          0 0  
          extperiph1                                        0            0    24000000    24000000          0 0  
root@tegra-ubuntu:/home/nvidia#

The extperiph3 was the clk name for CAM2_MCLK.

root@tegra-ubuntu:/home/nvidia# cat /sys/kernel/debug/clk/extperiph3/clk_rate 
19200000
root@tegra-ubuntu:/home/nvidia#
root@tegra-ubuntu:/home/nvidia# echo 24000000 > /sys/kernel/debug/clk/extperiph3/clk_rate 
bash: echo: write error: Permission denied
root@tegra-ubuntu:/home/nvidia# ls /sys/kernel/debug/clk/extperiph3/
clk_accuracy      clk_flags           clk_phase             clk_prepare_count  frequency_stats_table
clk_enable_count  clk_notifier_count  clk_possible_parents  clk_rate
root@tegra-ubuntu:/home/nvidia#

The method mentioned on the Clocks chapter of NVIDIA_Tegra_Linux_Driver_Package didn’t work.
Can anyone help me ?
Thanks !

@zhaozoz
Please check the latest document

The TX2 clocks are controlled by BPMP. For example, override the EMC rate with the following commands:
echo 1 > /sys/kernel/debug/bpmp/debug/clk/emc/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/emc/state
echo x > /sys/kernel/debug/bpmp/debug/clk/emc/rate

It’s my mistake.
What need to be modified is under the /sys/kernel/debug/bpmp/debug/clk dir.
Thanks @ShaneCCC

echo 24000000 > /sys/kernel/debug/bpmp/debug/clk/extperiph3/rate

And it works !