AM625SIP: eMMC vs DFU boot power draw

Hey Luke, 

I'm still traveling thru the 28th so I'll try my best to respond when I can.

Just to keep expectations clear, the Linux SDK is designed to enable as much as possible to help in the development process. The drawback of this is it keeps many thing on which will increase the power consumption. Hence even with the base wic image, there will still be a higher power consumption.

The power consumption of different boot methods hasn't been tested, but I don't believe it should impact the power consumption.

A53 cores are generally power optimized so changing the frequency won't change very much (depending on the application loading). Just be aware of the performance difference between 200MHz and 1250MHz.

The ~350mW number that you've pointed to is after optimizing clocking and peripherals on the AM62x EVM. This power consumption number maybe different for each application and use case, but we can try to optimizing for the customer to improve things.

I don't have an EVM with me so I haven't tested this myself.

First, make sure that any peripheral that is not being used is disabled in the device tree.

I'm assuming this is already done, but if not make a quick list of what peripherals the application needs. Then make sure anything not used is disabled in the device tree. It can be commented out from the board level device tree and adding 'status = "disabled";' in the k3-am62-<main/mcu/wkup>.dtsi.

Enable CBASS Auto Clock Gating

devmem2 0x43018280 w 0x00000000
devmem2 0x04518280 w 0x00000000

These are userspace Linux commands which should enable clock gating. When the CBASS is idle, it should put itself in a lower power state. How ofter this will trigger, I'm not sure because its based on how often the application needs to use the CBASS.

Optimizing the clocking via K3Conf

As mentioned before, the Linux SDK will enable as much as possible, so we can try to disable as much as we can.

If K3Conf isn't added in the package, you can find it here: https://git.ti.com/cgit/k3conf/k3conf/tree/

Use 'k3conf dump device' to dump all the devices. Just know that K3Conf is designed to support the superset of the devices so it may populate with peripherals that don't exist on the DUT.

You can try to disable as may of these devices that the application isn't using. This can be done by k3conf disable <device number> (use k3conf --help to fact check). Just know that there are dependencies on some devices that will impact if it can be disabled. For example, if its actively being used or has some security connection, it most likely won't be able to be disabled.

You can do the same with clocking via k3conf dump clock. This will list out every clock available and for peripherals not being used, you can either disable or slow down the clock. Again, use k3conf --help for the syntax. 

We can also go a little further by optimizing at the PLL level rather than the peripheral clocking level but K3Conf doesn't have control over this.

Other possible optimizations

Just off the top of my head, we can also

1. Power down the USB via the registers (assuming its not used)

2. Change the DDR FSP if the MT/s performance isn't critical.

3. There is a demo that runs on the default images. Can't remember if it runs on the base image, but try: 'systemctl stop weston; systemctl disable weston' then 'systemctl stop ti-apps-launcher; systemctl disable ti-apps-launcher'. If weston is needed, then you can just re-enable it. 

Best Regards,

Anshu