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IMX6UL-EVK Yocto Build Power Consumption

Question asked by julianwhiffen on Feb 22, 2019
Latest reply on Feb 22, 2019 by igorpadykov

I have an IMX6UL-EVK.  When I put in the SD card it was delivered with I can go through the power saving statements in AN5170 Sec 6.2.3 and reduce the power (I've just reading an ammeter on the 5V supply to the whole EVK as an initial test case).  It goes from 140mA after initial boot, down to 87mA after 'downing' eth0 and eth1 and then down to 41mA after echo 1 > /.../fb0/blank.  Finally hitting 39mA after echo mem > /sys/power/state.


The printk and governor statements don't appear to achieve any result.  I haven't implemented the x11 statement (as i'm not sure how yet!).


I've now completed an initial Yocto build

$ DISTRO=fsl-imx-wayland MACHINE=imx6ulevk source -b Build

$ bitbake core-image-base


and am using the SD card generated from this.  It begins at 116mA after initial boot, is not affected by downing eth0 or eth1 (since they appear to never have been bought up).  echo 1 > .../fb0/blank brings this to 98mA.  echo mem > /sys/power/state gets to 65mA.


I actually want the lowest possible power but in an active state (so mem > /sys/power/state is going tooo far) but am confused by the differences.  What do I have to do to the Yocto build from the current (active) 98mA to the (active) 41mA state that is achievable with the delivered card?