linux-kernel - Re: [PATCH v2] soundwire: intel_auxdevice: Fix system suspend/resume handling

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Message-ID: <CAJZ5v0gam8XmtwJ+8yp75EXmCXPrd3twSC_d39aMWw23YdCxfA@mail.gmail.com>
Date: Wed, 30 Apr 2025 16:24:10 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "Liao, Bard" <yung-chuan.liao@...ux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, Vinod Koul <vkoul@...nel.org>, 
	Pierre-Louis Bossart <pierre-louis.bossart@...ux.dev>, LKML <linux-kernel@...r.kernel.org>, 
	Linux PM <linux-pm@...r.kernel.org>, Sanyog Kale <sanyog.r.kale@...el.com>, 
	linux-sound@...r.kernel.org
Subject: Re: [PATCH v2] soundwire: intel_auxdevice: Fix system suspend/resume handling

On Wed, Apr 30, 2025 at 2:59 AM Liao, Bard
<yung-chuan.liao@...ux.intel.com> wrote:
>
>
>
> On 4/29/2025 3:50 AM, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > Before commit bca84a7b93fd ("PM: sleep: Use DPM_FLAG_SMART_SUSPEND
> > conditionally") the runtime PM status of the device in intel_resume()
> > had always been RPM_ACTIVE because setting DPM_FLAG_SMART_SUSPEND had
> > caused the core to call pm_runtime_set_active() for that device during
> > the "noirq" resume phase.  For this reason, the pm_runtime_suspended()
> > check in intel_resume() had never triggered and the code depending on
> > it had never run.  That had not caused any observable functional issues
> > to appear, so effectively the code in question had never been needed.
> >
> > After commit bca84a7b93fd the core does not call pm_runtime_set_active()
> > for all devices with DPM_FLAG_SMART_SUSPEND set any more and the code
> > depending on the pm_runtime_suspended() check in intel_resume() runs if
> > the device is runtime-suspended prior to a system-wide suspend
> > transition.  Unfortunately, when it runs, it breaks things due to the
> > attempt to runtime-resume bus->dev which most likely is not ready for a
> > runtime resume at that point.
> >
> > It also does other more-or-less questionable things.  Namely, it
> > calls pm_runtime_idle() for a device with a nonzero runtime PM usage
> > counter which has no effect (all devices have nonzero runtime PM
> > usage counters during system-wide suspend and resume).  It also calls
> > pm_runtime_mark_last_busy() for the device even though devices cannot
> > runtime-suspend during system-wide suspend and resume (because their
> > runtime PM usage counters are nonzero) and an analogous call is made
> > in the same function later.  Moreover, it sets the runtime PM status
> > of the device to RPM_ACTIVE before activating it.
> >
> > For the reasons listed above, remove that code altogether.
> >
> > On top of that, add a pm_runtime_disable() call to intel_suspend() to
> > prevent the device from being runtime-resumed at any point after
> > intel_suspend() has started to manipulate it because the changes
> > made by that function would be undone by a runtime-suspend of the
> > device.
> >
> > Next, once runtime PM has been disabled, the runtime PM status of the
> > device cannot change, so pm_runtime_status_suspended() can be used
> > instead of pm_runtime_suspended() in intel_suspend().
> >
> > Finally, make intel_resume() call pm_runtime_set_active() at the end to
> > set the runtime PM status of the device to "active" because it has just
> > been activated and re-enable runtime PM for it after that.
> >
> > Additionally, drop the setting of DPM_FLAG_SMART_SUSPEND from the
> > driver because it has no effect on devices handled by it.
> >
> > Fixes: bca84a7b93fd ("PM: sleep: Use DPM_FLAG_SMART_SUSPEND conditionally")
> > Reported-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> > Tested-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> >
> > v1 -> v2: New changelog
> >
> > Since it fixes a recent regression in 6.15-rc, I can route it through the
> > PM tree unless that would be a major concern.
> >
>
>  Acked-by: Bard Liao <yung-chuan.liao@...ux.intel.com>

Thanks, applied.