Suspend to memory in Debian Linaro distro


#1

I’m looking to work on some suspend functionality on a Dragonboard410c that has the USB hub and HDMI bridge removed in order to check how much power the part uses while sleeping. Reading here[1] and here[2], it seems like Qualcomm has no plans to add suspend to the boards but in the interest of getting some work done, I was wondering if there was any documentation on the PLL/RAM setting registers so that I can add that functionality myself?

I’ve verified that the board uses about 40mA when in the ‘freeze’ state, but that isn’t quite enough for our application.

I was actually digging around the Android source to see how they were going into the deeper sleep but couldn’t find the source.

Variscite[3] claims that they can get down to 4mA with their SOM and I would like to verify that. They too are just using the Debian Linaro distro, same as the Dragonboard.

[1] - Does db410c support suspend/resume functions?
[2] - Dragonboard power measurements
[3] - http://www.variscite.com/products/system-on-module-som/cortex-a53-krait/dart-sd410-qualcomm-snapdragon-410


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