Re: [PATCH v2 1/5] PM: ACPI/PCI: Resume all devices during hibernation

Rafael J. Wysocki
2019-07-02T15:59:45Z

On Mon, Jul 1, 2019 at 6:15 PM Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
>
> On Mon, Jul 01, 2019 at 12:44:25PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Both the PCI bus type and the ACPI PM domain avoid resuming
> > runtime-suspended devices with DPM_FLAG_SMART_SUSPEND set during
> > hibernation (before creating the snapshot image of system memory),
> > but that turns out to be a mistake. It leads to functional issues
> > and adds complexity that's hard to justify.
> >
> > For this reason, resume all runtime-suspended PCI devices and all
> > devices in the ACPI PM domains before creating a snapshot image of
> > system memory during hibernation.
> >
> > Fixes: 05087360fd7a (ACPI / PM: Take SMART_SUSPEND driver flag into account)
> > Fixes: c4b65157aeef (PCI / PM: Take SMART_SUSPEND driver flag into account)
> > Link: https://lore.kernel.org/linux-acpi/917d4399-2e22-67b1-9d54-808561f9083f@uwyo.edu/T/#maf065fe6e4974f2a9d79f332ab99dfaba635f64c
> > Reported-by: Robert R. Howell <RHowell@uwyo.edu>
> > Tested-by: Robert R. Howell <RHowell@uwyo.edu>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >
> > -> v2: No changes.
> >
> > ---
> > drivers/acpi/device_pm.c | 13 +++++++------
> > drivers/pci/pci-driver.c | 16 ++++++++--------
> > 2 files changed, 15 insertions(+), 14 deletions(-)
> >
> > Index: linux-pm/drivers/acpi/device_pm.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/device_pm.c
> > +++ linux-pm/drivers/acpi/device_pm.c
> > @@ -1155,13 +1155,14 @@ EXPORT_SYMBOL_GPL(acpi_subsys_resume_ear
> > int acpi_subsys_freeze(struct device *dev)
> > {
> > /*
> > - * This used to be done in acpi_subsys_prepare() for all devices and
> > - * some drivers may depend on it, so do it here. Ideally, however,
> > - * runtime-suspended devices should not be touched during freeze/thaw
> > - * transitions.
> > + * Resume all runtime-suspended devices before creating a snapshot
> > + * image of system memory, because the restore kernel generally cannot
> > + * be expected to always handle them consistently and they need to be
> > + * put into the runtime-active metastate during system resume anyway,
> > + * so it is better to ensure that the state saved in the image will be
> > + * alwyas consistent with that.
>
> alwyas -> always
>
> > */
> > - if (!dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND))
> > - pm_runtime_resume(dev);
> > + pm_runtime_resume(dev);
> >
> > return pm_generic_freeze(dev);
> > }
> > Index: linux-pm/drivers/pci/pci-driver.c
> > ===================================================================
> > --- linux-pm.orig/drivers/pci/pci-driver.c
> > +++ linux-pm/drivers/pci/pci-driver.c
> > @@ -1012,15 +1012,15 @@ static int pci_pm_freeze(struct device *
> > }
> >
> > /*
> > - * This used to be done in pci_pm_prepare() for all devices and some
> > - * drivers may depend on it, so do it here. Ideally, runtime-suspended
> > - * devices should not be touched during freeze/thaw transitions,
> > - * however.
> > + * Resume all runtime-suspended devices before creating a snapshot
> > + * image of system memory, because the restore kernel generally cannot
> > + * be expected to always handle them consistently and they need to be
> > + * put into the runtime-active metastate during system resume anyway,
> > + * so it is better to ensure that the state saved in the image will be
> > + * alwyas consistent with that.
>
> ditto

Thanks, I'll fix these up when applying the patch.