Messages in this thread | | | From | Linus Walleij <> | Date | Sun, 24 Jan 2021 00:21:13 +0100 | Subject | Re: [PATCH v6 2/2] iio: accel: Add support for the Bosch-Sensortec BMI088 |
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On Sat, Jan 23, 2021 at 4:35 PM Jonathan Cameron <jic23@kernel.org> wrote: > [Me] > > Next, I think it is better to let suspend/resume, i.e. system PM > > reuse runtime PM since you're implementing that. This is why > > we invented PM runtime force resume and force suspend. > > Here the driver is turning more off for full suspend than in the > runtime path. If that results in significant extra delay then > it's not appropriate to have that in the runtime suspend path.
I see the point.
The resume path calls bmi088_accel_enable() which incurs a 5ms delay.
The runtime resume path incurs a 1 ms delay.
The runtime autosuspend kicks in after 2 ms.
> Maybe the simplification of not doing the deeper power saving > mode is worth the extra power cost or extra delay, but > I'm not yet convinced.
I would personally set the autosuspend to ~20ms and just use one path and take a hit of 5 ms whenever we go down between measures if it is a system that is for human interaction, but for control systems this more complex set-up may be better for response latencies.
The current approach may be better tuned to perfection and we are all perfectionists :D
I'm just worrying a little about bugs and maintainability.
Yours, Linus Walleij
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