Use the Bus Frequency driver to slow down DDR, AHB, and AXI bus frequency in the SoC when the IPs which need high bus frequency are not working.

In this release, the bus frequency driver is enabled by default. It significantly saves the power consumption in Android early suspend mode (playing audio with the screen off). If you want to enable or disable it, perform the following command in the console:


$ echo 0 >


$ echo 1 > 

Note that if you use Ethernet, the up operation enables the FEC clock and forces bus frequency to be high. That means you cannot go into low bus mode anymore, regardless of whether the Ethernet cable is plugged or unplugged. Therefore, if you want the system to go into the low bus mode, you must issue

netcfg eth0 down 

to shut down the FEC manually. If you’re going to use FEC again, issue

netcfg eth0 up 

manually. When FEC is shut down with clock gated, the PHY cannot detect your cable in/out events.