[PATCH v4 2/5] PCI: Put PCIe ports with downstream devices into D3 at hibernate
Ville Syrjälä
ville.syrjala at linux.intel.com
Thu Jul 17 22:35:03 UTC 2025
On Mon, Jun 16, 2025 at 12:50:16PM -0500, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello at amd.com>
>
> For the suspend flow PCIe ports that have downstream devices are put into
> the appropriate D3 state when children are not in D0. For the hibernate
> flow, PCIe ports with downstream devices stay in D0 however. This can
> lead to PCIe ports that are remained powered on needlessly during
> hibernate.
>
> Adjust the pci_pm_poweroff_noirq() to follow the same flow as
> pci_pm_suspend_noirq() in that PCIe ports that are power manageable should
> without downstream devices in D0 should be put into their appropriate
> sleep state.
>
> Cc: AceLan Kao <acelan.kao at canonical.com>
> Cc: Kai-Heng Feng <kaihengf at nvidia.com>
> Cc: Mark Pearson <mpearson-lenovo at squebb.ca>
> Cc: Denis Benato <benato.denis96 at gmail.com>
> Cc: Merthan Karakaş <m3rthn.k at gmail.com>
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> ---
> v4:
> * Use helper even when CONFIG_SUSPEND not set (LKP robot)
> v3:
> * Split out common code between suspend_noirq() and poweroff_noirq()
> to a helper function
> * https://lore.kernel.org/linux-pm/20250609024619.407257-1-superm1@kernel.org/T/#me6db0fb946e3d604a8f3d455128844ed802c82bb
> ---
> drivers/pci/pci-driver.c | 94 ++++++++++++++++++++++++++--------------
> 1 file changed, 61 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 0d4c67829958b..f7a0c23515718 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -759,6 +759,56 @@ static void pci_pm_complete(struct device *dev)
>
> #endif /* !CONFIG_PM_SLEEP */
>
> +#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATE_CALLBACKS)
> +/**
> + * pci_pm_set_prepare_bus_pm
> + * @pci_dev: pci device
> + *
> + * Prepare the device to go into a low power state by saving state
> + * and configure bus PM policy.
> + *
> + * Return: TRUE for bus PM will be used
> + * FALSE for bus PM will be skipped
> + */
> +static bool pci_pm_set_prepare_bus_pm(struct pci_dev *pci_dev)
> +{
> + if (!pci_dev->state_saved) {
> + pci_save_state(pci_dev);
> +
> + /*
> + * If the device is a bridge with a child in D0 below it,
> + * it needs to stay in D0, so check skip_bus_pm to avoid
> + * putting it into a low-power state in that case.
> + */
> + if (!pci_dev->skip_bus_pm && pci_power_manageable(pci_dev))
> + pci_prepare_to_sleep(pci_dev);
> + }
> +
> + pci_dbg(pci_dev, "PCI PM: Sleep power state: %s\n",
> + pci_power_name(pci_dev->current_state));
> +
> + if (pci_dev->current_state == PCI_D0) {
> + pci_dev->skip_bus_pm = true;
> + /*
> + * Per PCI PM r1.2, table 6-1, a bridge must be in D0 if any
> + * downstream device is in D0, so avoid changing the power state
> + * of the parent bridge by setting the skip_bus_pm flag for it.
> + */
> + if (pci_dev->bus->self)
> + pci_dev->bus->self->skip_bus_pm = true;
> + }
> +
> + if (pci_dev->skip_bus_pm && pm_suspend_no_platform()) {
> + pci_dbg(pci_dev, "PCI PM: Skipped\n");
> + return FALSE;
> + }
> +
> + pci_pm_set_unknown_state(pci_dev);
> +
> + return TRUE;
> +}
> +#endif /* CONFIG_SUSPEND || CONFIG_HIBERNATE_CALLBACKS */
> +
> #ifdef CONFIG_SUSPEND
> static void pcie_pme_root_status_cleanup(struct pci_dev *pci_dev)
> {
> @@ -878,38 +928,8 @@ static int pci_pm_suspend_noirq(struct device *dev)
> }
> }
>
> - if (!pci_dev->state_saved) {
> - pci_save_state(pci_dev);
> -
> - /*
> - * If the device is a bridge with a child in D0 below it,
> - * it needs to stay in D0, so check skip_bus_pm to avoid
> - * putting it into a low-power state in that case.
> - */
> - if (!pci_dev->skip_bus_pm && pci_power_manageable(pci_dev))
> - pci_prepare_to_sleep(pci_dev);
> - }
> -
> - pci_dbg(pci_dev, "PCI PM: Suspend power state: %s\n",
> - pci_power_name(pci_dev->current_state));
> -
> - if (pci_dev->current_state == PCI_D0) {
> - pci_dev->skip_bus_pm = true;
> - /*
> - * Per PCI PM r1.2, table 6-1, a bridge must be in D0 if any
> - * downstream device is in D0, so avoid changing the power state
> - * of the parent bridge by setting the skip_bus_pm flag for it.
> - */
> - if (pci_dev->bus->self)
> - pci_dev->bus->self->skip_bus_pm = true;
> - }
> -
> - if (pci_dev->skip_bus_pm && pm_suspend_no_platform()) {
> - pci_dbg(pci_dev, "PCI PM: Skipped\n");
> + if (!pci_pm_set_prepare_bus_pm(pci_dev))
> goto Fixup;
> - }
> -
> - pci_pm_set_unknown_state(pci_dev);
>
> /*
> * Some BIOSes from ASUS have a bug: If a USB EHCI host controller's
> @@ -1136,6 +1156,8 @@ static int pci_pm_poweroff(struct device *dev)
> struct pci_dev *pci_dev = to_pci_dev(dev);
> const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
>
> + pci_dev->skip_bus_pm = false;
> +
> if (pci_has_legacy_pm_support(pci_dev))
> return pci_legacy_suspend(dev, PMSG_HIBERNATE);
>
> @@ -1199,8 +1221,8 @@ static int pci_pm_poweroff_noirq(struct device *dev)
> return error;
> }
>
> - if (!pci_dev->state_saved && !pci_has_subordinate(pci_dev))
> - pci_prepare_to_sleep(pci_dev);
> + if (!pci_pm_set_prepare_bus_pm(pci_dev))
> + goto Fixup;
This looks like it's doing similar stuff to what I wanted to do here:
https://lore.kernel.org/linux-pci/20240925144526.2482-2-ville.syrjala@linux.intel.com/
and a bunch of other stuff that seems to lack an explanation:
- the pci_has_subordinate() check is disappearing
- pci_save_state() is now getting called for the poweroff path
- same for pci_pm_set_unknown_state()
- the pci_pm_bridge_power_up_actions() call is being added to
pci_pm_restore_noirq() for some reason
> /*
> * The reason for doing this here is the same as for the analogous code
> @@ -1209,6 +1231,7 @@ static int pci_pm_poweroff_noirq(struct device *dev)
> if (pci_dev->class == PCI_CLASS_SERIAL_USB_EHCI)
> pci_write_config_word(pci_dev, PCI_COMMAND, 0);
>
> +Fixup:
> pci_fixup_device(pci_fixup_suspend_late, pci_dev);
>
> return 0;
> @@ -1218,10 +1241,15 @@ static int pci_pm_restore_noirq(struct device *dev)
> {
> struct pci_dev *pci_dev = to_pci_dev(dev);
> const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> + pci_power_t prev_state = pci_dev->current_state;
> + bool skip_bus_pm = pci_dev->skip_bus_pm;
>
> pci_pm_default_resume_early(pci_dev);
> pci_fixup_device(pci_fixup_resume_early, pci_dev);
>
> + if (!skip_bus_pm && prev_state == PCI_D3cold)
> + pci_pm_bridge_power_up_actions(pci_dev);
> +
> if (pci_has_legacy_pm_support(pci_dev))
> return 0;
>
> --
> 2.43.0
--
Ville Syrjälä
Intel
More information about the dri-devel
mailing list