On Thu, Jan 12, 2023 at 9:21 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Wed, Jan 11, 2023 at 11:38:55AM +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> > > --- > > > > 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_D3_HOT) > > The comment suggests that this should check for "<= ACPI_STATE_D2" > (not ACPI_STATE_D3_HOT). Or is there some subtlety here that I'm > missing? No, this is a mistake. I'll send a v4.
