ubuntu@ubuntu-desktop:~$ sudo grep "aud_mclk\|i2s1" /sys/kernel/debug/clk/clk_summary
[sudo] password for ubuntu: 
 i2s1_sync_input                                            0            0           0           0          0 0  
    i2s1_sync_clk                                           0            0           0           0          0 0  
             i2s1                                           0            0     2137043     1536000          0 0  
          aud_mclk                                          1            1    12000000    12000000          0 0