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

Mika Westerberg
2019-07-01T16:15:56Z

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

> */
> - if (!dev_pm_smart_suspend_and_suspended(dev)) {
> - pm_runtime_resume(dev);
> - pci_dev->state_saved = false;
> - }
> + pm_runtime_resume(dev);
> + pci_dev->state_saved = false;
>
> if (pm->freeze) {
> int error;
>
>
>