On Mon, Jun 16, 2025 at 12:50:16PM -0500, Mario Limonciello wrote: > From: Mario Limonciello <mario.limoncie...@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.
I suppose by "appropriate D3 state", you mean the Port is put in D3cold if all children are in D3cold, or D3hot if they are all in D1-D3hot? PM-illiterate folks like me need some help to know what is "appropriate" :) This refers specifically to "PCIe ports", but it looks like the code applies to PCI bridges in general, so maybe it should just say "bridges"? s/ports that are remained powered on/ports that remain powered on/ (or "bridges that remain powered on") > 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. Extra "should" in this sentence, I guess? (s/power manageable should/power manageable/) Also "PCIe ports" here, maybe should be "bridges"? > Cc: AceLan Kao <acelan....@canonical.com> > Cc: Kai-Heng Feng <kaihe...@nvidia.com> > Cc: Mark Pearson <mpearson-len...@squebb.ca> > Cc: Denis Benato <benato.deni...@gmail.com> > Cc: Merthan Karakaş <m3rth...@gmail.com> > Signed-off-by: Mario Limonciello <mario.limoncie...@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-supe...@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. I guess "configure bus PM policy" must mean "if this device is in D0, set skip_bus_pm = true for the device and any upstream bridge so we won't change their power state"? > + * 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) The "pci_pm_set_prepare_bus_pm" name doesn't immediately suggest a property that can be true or false. It complicates things a bit when a bool function has side effects in addition to giving a yes/no or true/false answer. Not sure whether or how this could be improved. And it's a little confusing that we return false when we set skip_bus_pm = true (mostly). It's tough to keep track of what true/false means. > +{ > + 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; "true" and "false" instead of "TRUE" and "FALSE". > +} > +#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); This part looks like it's mostly factoring this code out to pci_pm_set_prepare_bus_pm(). Would it be practical to split that factoring to a patch that makes no functional change? I'm wondering if that would make the functional change smaller and easier to understand. > /* > * 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; > > /* > * 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 >
