Re: [PATCH v2] PM / sleep: Let devices force direct_complete

From: Rafael J. Wysocki
Date: Fri May 15 2015 - 10:29:54 EST

On Friday, May 15, 2015 03:25:00 PM Tomeu Vizoso wrote:
> On 14 May 2015 at 21:56, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> > On Thursday, May 14, 2015 03:37:52 PM Tomeu Vizoso wrote:
> >> Introduce a new per-device flag power.force_direct_complete that will
> >> instruct the PM core to let that device remain in runtime suspend when
> >> the system goes into a sleep power state, regardless of the PM state of
> >> any of its descendants.
> >>
> >> This is needed because otherwise it would be needed to get dozens of
> >> drivers to implement the prepare() callback and be runtime PM active
> >> even if they don't have a 1-to-1 relationship with a piece of HW.
> >>
> >> This only applies to devices that aren't wakeup-capable, as those would
> >> need to setup their IRQs as wakeup-capable in their prepare() callbacks.
> >>
> >> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> >
> > Well, my idea of a "direct complete" flag was a bit different and I have
> > a concern with this particular implementation. ->
> Yeah, I started like that but then realized that, at least in the
> uvcvideo case, it doesn't know at probe() time how many descendants
> it's going to have.
> This was discussed in:

I guess the solution may be to inherit the parent setting when creating
a device in those cases, so the ucvideo will set the flag for the top-most
device at probe() time and the devices below it will simply inherit the

This way or another, I would very much prefer to restrict this new thing
to device_prepare().

I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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