PM regression with commit 5de85b9d57ab PM runtime re-init in v4.5-rc1

[Ulf Hansson]

On 4 February 2016 at 23:09, Alan Stern <stern at rowland.harvard.edu> wrote:
> On Thu, 4 Feb 2016, Ulf Hansson wrote:
>
>> I am really not questioning the autosuspend feature at all, it's a
>> really great feature!
>>
>> Now, I question the minor benefit we actually gain from having the
>> runtime PM core to update the mark in rpm_resume().
>
> As Tony pointed out, it prevents some devices from going to sleep right
> away.

Because their drivers don't care to update the last busy mark!?

>
>> To me, the best decision when to update the mark is know by the
>> driver/subsystem for the device and not the core.
>>
>> In most cases the mark will be updated after a request has been
>> completed, which leads to one unnecessary update at rpm_resume().
>
> Sure, but that update is a simple assignment statement.  It's about as
> cheap as you can get, short of doing nothing at all.

Valid point. I rest my case. :-)

Thanks for the discussion.

[...]

Kind regards
Uffe