linux-kernel - Re: [PATCH v1 0/9] PM: Reconcile different driver options for runtime PM integration with system sleep

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Message-ID: <CAPDyKFq7gydO0uioA53LqXk-N+Bjp4bwkaRRzMeWv+F=zpy2Jw@mail.gmail.com>
Date: Thu, 26 Jun 2025 12:41:10 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, Linux PM <linux-pm@...r.kernel.org>, 
	LKML <linux-kernel@...r.kernel.org>, Linux ACPI <linux-acpi@...r.kernel.org>, 
	Linux PCI <linux-pci@...r.kernel.org>, 
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v1 0/9] PM: Reconcile different driver options for runtime
 PM integration with system sleep

On Thu, 26 Jun 2025 at 12:34, Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Thu, Jun 26, 2025 at 12:31 PM Ulf Hansson <ulf.hansson@...aro.org> wrote:
> >
> > On Wed, 25 Jun 2025 at 21:25, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> > >
> > > Hi Everyone,
> > >
> > > This series addresses a couple of issues related to the integration of runtime
> > > PM with system sleep I was talking about at the OSMP-summit 2025:
> > >
> > > https://lwn.net/Articles/1021332/
> > >
> > > Most importantly, DPM_FLAG_SMART_SUSPEND cannot be used along with
> > > pm_runtime_force_suspend/resume() due to some conflicting expectations
> > > about the handling of device runtime PM status between these functions
> > > and the PM core.
> > >
> > > Also pm_runtime_force_suspend/resume() currently cannot be used in PCI
> > > drivers and in drivers that collaborate with the general ACPI PM domain
> > > because they both don't expect their mid-layer runtime PM callbacks to
> > > be invoked during system-wide suspend and resume.
> > >
> > > Patch [1/9] is a preparatory cleanup changing the code to use 'true' and
> > > 'false' as needs_force_resume flag values for consistency.
> > >
> > > Patch [2/9] makes pm_runtime_force_suspend() check needs_force_resume along
> > > with the device's runtime PM status upfront, and bail out if it is set,
> > > which allows runtime PM status updates to be eliminated from both that function
> > > and pm_runtime_force_resume().
> > >
> > > Patch [3/9] causes the smart_suspend flag to be taken into account by
> > > pm_runtime_force_resume() which allows it to resume devices with smart_suspend
> > > set whose runtime PM status has been changed to RPM_ACTIVE by the PM core at
> > > the beginning of system resume.  After this patch, drivers that use
> > > pm_runtime_force_suspend/resume() can also set DPM_FLAG_SMART_SUSPEND which
> > > may be useful, for example, if devices handled by them are involved in
> > > dependency chains with other devices setting DPM_FLAG_SMART_SUSPEND.
> > >
> > > The next two patches, [4-5/9], put pm_runtime_force_suspend/resume()
> > > and needs_force_resume under CONFIG_PM_SLEEP for consistency and also
> > > because using them outside system-wide PM transitions really doesn't make
> > > sense.
> > >
> > > Patch [6/9] makes the code for getting a runtime PM callback for a device
> > > a bit more straightforward in preparation for the subsequent changes.
> >
> > I can't find this one. Seems like you did not submit it.
> >
> > Perhaps make a resend and fixup the patch-numbering too?
>
> I'm going to send a v2, but the patch in question is here (wrong number):
>
> https://lore.kernel.org/linux-acpi/3306233.5fSG56mABF@rjwysocki.net/

No, that's patch2 (which was named pacth0). :-) Nevermind, I think we
made some progress so I am awaiting a v2 before continuing my reviews.

Kind regards
Uffe