i.MX 8M Mini Power Optimization Study

[david_vekony]

Hi,

Back in January (2019.01.11) our company got a presentation titled "i.MX 8M Mini Power Optimization Study, Android P Operating System" from Alexandra Dopplinger.

We'd like to look at the actual SW changes made in order to reduce the power (those are listed on slide 2 and mainly slide 5). Can someone provide us those?

Thanks,

David Vekony

Cognex

[gusarambula]

Hello David Vekony,

My apologies for the delay.

The changes listed below are not available on any BSP and we couldn't locate patches that would apply them. However, these would be relatively straightforward changed in which NXP Professional Services may help.

> Android
− Change the display to smaller resolution (720x576) in U Boot boot arguments
− UI Composer target pixel format change from 32 bit RGBX to RGB565

> U Boot 
− Reduce DDR peak bandwidth from 3200MTS to 1600MTS
− Change BUCK regulator #5 from 0.9V to 0.8V

> Linux Kernel
− DTS file changes
 − Remove 2 CPU cores, limit CPU to 800MHz, reduce CPU Idle enter/exit thresholds, couple USB clock with USB
power domain, use OCRAM buffer for SDMA
    Disable all not listed in customer specific block diagram
−Driver changes
    Limit CPU to 800MHz
    Adjust main AXI NOC to low bus mode in BusFREQ and lower delayed work from 1s to 200ms
    Make high bus request ONLY for video playback
   Disable unused clock gates
   Logic added to turn off 3D clock if ONLY GPU 2D is active

Regards.