Re: [PATCH 00/51] treewide: Switch to __pm_runtime_put_autosuspend()

Uwe Kleine-König
2024-10-08T20:39:42Z

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Hello,

On Mon, Oct 07, 2024 at 09:49:24PM +0300, Laurent Pinchart wrote:
> On Fri, Oct 04, 2024 at 04:38:36PM +0200, Ulf Hansson wrote:
> > On Fri, 4 Oct 2024 at 11:41, Sakari Ailus <sakari.ailus@linux.intel.com> wrote:
> > >
> > > Hello everyone,
> > >
> > > This set will switch the users of pm_runtime_put_autosuspend() to
> > > __pm_runtime_put_autosuspend() while the former will soon be re-purposed
> > > to include a call to pm_runtime_mark_last_busy(). The two are almost
> > > always used together, apart from bugs which are likely common. Going
> > > forward, most new users should be using pm_runtime_put_autosuspend().
> > >
> > > Once this conversion is done and pm_runtime_put_autosuspend() re-purposed,
> > > I'll post another set to merge the calls to __pm_runtime_put_autosuspend()
> > > and pm_runtime_mark_last_busy().
> >
> > That sounds like it could cause a lot of churns.
> >
> > Why not add a new helper function that does the
> > pm_runtime_put_autosuspend() and the pm_runtime_mark_last_busy()
> > things? Then we can start moving users over to this new interface,
> > rather than having this intermediate step?
>
> I think the API would be nicer if we used the shortest and simplest
> function names for the most common use cases. Following
> pm_runtime_put_autosuspend() with pm_runtime_mark_last_busy() is that
> most common use case. That's why I like Sakari's approach of repurposing
> pm_runtime_put_autosuspend(), and introducing
> __pm_runtime_put_autosuspend() for the odd cases where
> pm_runtime_mark_last_busy() shouldn't be called.

That's ok for me. However this patch series isn't the optimal path to
there because most drivers (i.e. those that already today do
pm_runtime_mark_last_busy() in combination with
pm_runtime_put_autosuspend()) have to be patched twice.

The saner route is: Only convert the drivers with a sole
pm_runtime_put_autosuspend() (i.e. without pm_runtime_mark_last_busy())
to __pm_runtime_put_autosuspend(). Then add the mark_last_busy() bits to
pm_runtime_put_autosuspend() and then drop the explicit calls to
pm_runtime_mark_last_busy() before pm_runtime_put_autosuspend().

(Note this doesn't take into account Rafael's position that
pm_runtime_put() might be the saner option. My argument applies for that
conversion analogously.)

Best regards
Uwe

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