Re: Controlling device power management from terminal

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On Mon, 25 Jul 2022 at 23:27, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote:
>
> On Mon, Jul 25, 2022 at 10:48 AM Crt Mori <cmo@xxxxxxxxxxx> wrote:
> >
> > Hi,
> > I am implementing the power saving modes for mlx90632 device driver
> > and while I have implemented routines for SET_RUNTIME_PM_OPS
> > (runtime_pm_suspend and runtime_pm_resume) I am not able to find out
> > how to trigger them from the terminal.
> >
> > It could be that my driver code for power management implementation is
> > incomplete and I need to initialize something more.
> >
> > Maybe it is helpful, but the power submodule of the device contains below files:
> >
> > $ ls -al /sys/bus/iio/devices/iio\:device0/power
> > total 0
> > drwxrwxr-x 2 root gpio    0 Apr  6 14:17 .
> > drwxrwxr-x 3 root gpio    0 Apr  6 14:17 ..
> > -rw-rw-r-- 1 root gpio 4096 Apr  6 14:17 async
> > -rw-rw-r-- 1 root gpio 4096 Apr  6 14:17 autosuspend_delay_ms
> > -rw-rw-r-- 1 root gpio 4096 Apr  6 14:18 control
> > -r--r--r-- 1 root gpio 4096 Apr  6 14:17 runtime_active_kids
> > -r--r--r-- 1 root gpio 4096 Apr  6 14:17 runtime_active_time
> > -r--r--r-- 1 root gpio 4096 Apr  6 14:17 runtime_enabled
> > -r--r--r-- 1 root gpio 4096 Apr  6 14:17 runtime_status
> > -r--r--r-- 1 root gpio 4096 Apr  6 14:17 runtime_suspended_time
> > -r--r--r-- 1 root gpio 4096 Apr  6 14:17 runtime_usage
> >
> > And control is already set to "auto" which according to documentation
> > should allow the PM.
>
> 'auto' should enable it. So, whenever the driver thinks it's a time to
> power off/on the device it will call the methods.
>
> You may hack a bit to enable autosuspend (which often is not a good
> idea for IIO sensors) and see it done automatically after some time.

So the idea is to wait? How would I enable autosuspend - by lowering
the autosusped_delay_ms? How does the driver decide that it is time to
power off/on?

Do I need something else enabled to have this done automatically?
Autosuspend is 5000 in my case which would mean 5 seconds, so I am
quite sure I waited that long and I did not see printk's from the
driver.


>
> --
> With Best Regards,
> Andy Shevchenko



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