megi's PinePhone Development Log RSS


2023–05–28: Some regressions in power use in system sleep on original Pinephone

With my new setup, I've noticed that original Pinephone again has the issue with touchscreen consuming a lot of power during sleep.

It turns out just holding it in reset doesn't work for some reason. Is reset signal even connected to the touch controller? It's hard to see how the controller can be held in reset during system sleep and yet vary the power consumption when the screen is touched.

Something is fishy in there.

Truly powering the touch controller down

So instead of „hold in reset“ approach, I decided to try to power down the regulators powering the controller. This is not as simple as it sounds, because these regulators are shared by multiple devices, some of which don't have code to power them down during sleep, or actively don't want to power them down.

After these patches, original Pinephone again has much improved power use in deep sleep, not affected by the misbehaving controller that refuses to sleep.