On Thu, Jan 12, 2023 at 09:51:24PM +0100, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > It is generally questionable to allow a PCI bridge to go into D3 if > it has _S0W returning D2 or a shallower power state, so modify > acpi_pci_bridge_d3(() to always take the return value of _S0W for the > target bridge into accout. That is, make it return 'false' if _S0W > returns D2 or a shallower power state for the target bridge regardless > of its ancestor PCIe Root Port properties. Of course, this also causes > 'false' to be returned if the PCIe Root Port itself is the target and > its _S0W returns D2 or a shallower power state. > > However, still allow bridges without _S0W that are power-manageable via > ACPI to enter D3 to retain the current code behavior in that case. > > Link: https://lore.kernel.org/linux-pci/20221031223356.32570-1-mario.limonciello@xxxxxxx/ > Reported-by: Mario Limonciello <mario.limonciello@xxxxxxx> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Applied to pci/pm for v6.3, thanks! It'd be great if we could include a short description of the problems users might see. I think the original problem was that on some AMD systems we put a USB4 router in D3 when it should remain in D0. And I assume this means something doesn't wake up when it should? Or maybe we miss a hotplug event? If somebody has an example or some text, I'll add it to the commit log. > --- > > v3 -> v4: > * Use ACPI_STATE_D2 in the checks in acpi_pci_bridge_d3(). > > v2 -> v3: > * Use rpadev for the ACPI companion of the Root Port in acpi_pci_bridge_d3(() > to avoid confusion. > * Make the function evaluating _S0W return the value produced by it or "unknown > state" on errors and let its caller deal with that value. > > --- > drivers/acpi/device_pm.c | 19 +++++++++++++++++++ > drivers/pci/pci-acpi.c | 45 +++++++++++++++++++++++++++++++-------------- > include/acpi/acpi_bus.h | 1 + > 3 files changed, 51 insertions(+), 14 deletions(-) > > Index: linux-pm/drivers/pci/pci-acpi.c > =================================================================== > --- linux-pm.orig/drivers/pci/pci-acpi.c > +++ linux-pm/drivers/pci/pci-acpi.c > @@ -976,24 +976,41 @@ bool acpi_pci_power_manageable(struct pc > bool acpi_pci_bridge_d3(struct pci_dev *dev) > { > struct pci_dev *rpdev; > - struct acpi_device *adev; > - acpi_status status; > - unsigned long long state; > + struct acpi_device *adev, *rpadev; > const union acpi_object *obj; > > if (acpi_pci_disabled || !dev->is_hotplug_bridge) > return false; > > - /* Assume D3 support if the bridge is power-manageable by ACPI. */ > - if (acpi_pci_power_manageable(dev)) > - return true; > + adev = ACPI_COMPANION(&dev->dev); > + if (adev) { > + /* > + * If the bridge has _S0W, whether or not it can go into D3 > + * depends on what is returned by that object. In particular, > + * if the power state returned by _S0W is D2 or shallower, > + * entering D3 should not be allowed. > + */ > + if (acpi_dev_power_state_for_wake(adev) <= ACPI_STATE_D2) > + return false; > + > + /* > + * Otherwise, assume that the bridge can enter D3 so long as it > + * is power-manageable via ACPI. > + */ > + if (acpi_device_power_manageable(adev)) > + return true; > + } > > rpdev = pcie_find_root_port(dev); > if (!rpdev) > return false; > > - adev = ACPI_COMPANION(&rpdev->dev); > - if (!adev) > + if (rpdev == dev) > + rpadev = adev; > + else > + rpadev = ACPI_COMPANION(&rpdev->dev); > + > + if (!rpadev) > return false; > > /* > @@ -1001,15 +1018,15 @@ bool acpi_pci_bridge_d3(struct pci_dev * > * doesn't supply a wakeup GPE via _PRW, it cannot signal hotplug > * events from low-power states including D3hot and D3cold. > */ > - if (!adev->wakeup.flags.valid) > + if (!rpadev->wakeup.flags.valid) > return false; > > /* > - * If the Root Port cannot wake itself from D3hot or D3cold, we > - * can't use D3. > + * In the bridge-below-a-Root-Port case, evaluate _S0W for the Root Port > + * to verify whether or not it can signal wakeup from D3. > */ > - status = acpi_evaluate_integer(adev->handle, "_S0W", NULL, &state); > - if (ACPI_SUCCESS(status) && state < ACPI_STATE_D3_HOT) > + if (rpadev != adev && > + acpi_dev_power_state_for_wake(rpadev) <= ACPI_STATE_D2) > return false; > > /* > @@ -1018,7 +1035,7 @@ bool acpi_pci_bridge_d3(struct pci_dev * > * bridges *below* that Root Port can also signal hotplug events > * while in D3. > */ > - if (!acpi_dev_get_property(adev, "HotPlugSupportInD3", > + if (!acpi_dev_get_property(rpadev, "HotPlugSupportInD3", > ACPI_TYPE_INTEGER, &obj) && > obj->integer.value == 1) > return true; > Index: linux-pm/drivers/acpi/device_pm.c > =================================================================== > --- linux-pm.orig/drivers/acpi/device_pm.c > +++ linux-pm/drivers/acpi/device_pm.c > @@ -484,6 +484,25 @@ void acpi_dev_power_up_children_with_adr > acpi_dev_for_each_child(adev, acpi_power_up_if_adr_present, NULL); > } > > +/** > + * acpi_dev_power_state_for_wake - Deepest power state for wakeup signaling > + * @adev: ACPI companion of the target device. > + * > + * Evaluate _S0W for @adev and return the value produced by it or return > + * ACPI_STATE_UNKNOWN on errors (including _S0W not present). > + */ > +u8 acpi_dev_power_state_for_wake(struct acpi_device *adev) > +{ > + unsigned long long state; > + acpi_status status; > + > + status = acpi_evaluate_integer(adev->handle, "_S0W", NULL, &state); > + if (ACPI_FAILURE(status)) > + return ACPI_STATE_UNKNOWN; > + > + return state; > +} > + > #ifdef CONFIG_PM > static DEFINE_MUTEX(acpi_pm_notifier_lock); > static DEFINE_MUTEX(acpi_pm_notifier_install_lock); > Index: linux-pm/include/acpi/acpi_bus.h > =================================================================== > --- linux-pm.orig/include/acpi/acpi_bus.h > +++ linux-pm/include/acpi/acpi_bus.h > @@ -533,6 +533,7 @@ int acpi_bus_update_power(acpi_handle ha > int acpi_device_update_power(struct acpi_device *device, int *state_p); > bool acpi_bus_power_manageable(acpi_handle handle); > void acpi_dev_power_up_children_with_adr(struct acpi_device *adev); > +u8 acpi_dev_power_state_for_wake(struct acpi_device *adev); > int acpi_device_power_add_dependent(struct acpi_device *adev, > struct device *dev); > void acpi_device_power_remove_dependent(struct acpi_device *adev, > > >
