Hi Bjorn, On 8/13/21 11:10 PM, Bjorn Helgaas wrote: >>>> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c >>>> index eaddbf701759..dae021322b3f 100644 >>>> --- a/drivers/pci/pci-acpi.c >>>> +++ b/drivers/pci/pci-acpi.c >>>> @@ -952,7 +952,6 @@ static bool acpi_pci_bridge_d3(struct pci_dev *dev) >>>> return false; >>>> >>>> /* Assume D3 support if the bridge is power-manageable by ACPI. */ >>>> - pci_set_acpi_fwnode(dev); >>>> adev = ACPI_COMPANION(&dev->dev); >>> I *think* the Root Port code farther down in this function is also now >>> unnecessary: >>> >>> acpi_pci_bridge_d3(...) >>> { >>> ... >>> root = pcie_find_root_port(dev); >>> adev = ACPI_COMPANION(&root->dev); >>> if (root == dev) { >>> /* >>> * It is possible that the ACPI companion is not yet bound >>> * for the root port so look it up manually here. >>> */ >>> if (!adev && !pci_dev_is_added(root)) >>> adev = acpi_pci_find_companion(&root->dev); >>> } >>> >>> Since we're now setting the ACPI_COMPANION for every pci_dev long >>> before we get here, I think this could now be simplified to something >>> like this: >>> >>> acpi_pci_bridge_d3(...) >>> { >>> if (!dev->is_hotplug_bridge) >>> return false; >>> >>> adev = ACPI_COMPANION(&dev->dev); >>> if (adev && acpi_device_power_manageable(adev)) >>> return true; >>> >>> root = pcie_find_root_port(dev); >>> if (!root) >>> return false; >>> >>> adev = ACPI_COMPANION(&root->dev); >>> if (!adev) >>> return false; >>> >>> rc = acpi_dev_get_property(dev, "HotPlugSupportInD3", >>> ACPI_TYPE_INTEGER, &val); >>> if (rc < 0) >>> return false; >>> >>> return val == 1; >>> } >> Agree, thanks for your suggestion. Yes, it can be simplified too. >> Can I do something like this using the unified device property API? >> >> static bool acpi_pci_bridge_d3(struct pci_dev *dev) >> { >> struct acpi_device *adev; >> struct pci_dev *root; >> u8 val; >> >> if (!dev->is_hotplug_bridge) >> return false; >> >> adev = ACPI_COMPANION(&dev->dev); >> if (adev && acpi_device_power_manageable(adev)) >> return true; >> >> root = pcie_find_root_port(dev); >> if (!root) >> return false; >> >> if (device_property_read_u8(&root->dev, "HotPlugSupportInD3", &val)) >> return false; > I guess that might be OK. > > TBH I don't really like the device_property_read_u8() thing because > (1) we know this is an ACPI property and I don't see a reason to use > an "generic" interface that doesn't buy us anything, and (2) the > connection to the source of the data (a _DSD method) is really, really > hard to find. > > Admittedly, it's still pretty hard to connect acpi_dev_get_property() > with "_DSD". The only real clue is the comment about "Look for a > special _DSD property ..." > Does it satisfy you if I change the comment and still use device_property API? static bool acpi_pci_bridge_d3(struct pci_dev *dev) { struct pci_dev *rpdev; u8 val; if (!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; /* * Look for 'HotPlugSupportInD3' property for the root port and if * it is set we know the hierarchy behind it supports D3 just fine. */ rpdev = pcie_find_root_port(dev); if (!rpdev) return false; if (device_property_read_u8(&rpdev->dev, "HotPlugSupportInD3", &val)) return false; return val == 1; } If not, I'll do changes like this. static bool acpi_pci_bridge_d3(struct pci_dev *dev) { const union acpi_object *obj; struct acpi_device *adev; struct pci_dev *rpdev; if (!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; /* * Look for 'HotPlugSupportInD3' property for the root port and if * it is set we know the hierarchy behind it supports D3 just fine. */ rpdev = pcie_find_root_port(dev); if (!rpdev) return false; adev = ACPI_COMPANION(&rpdev->dev); if (!adev) return false; if (acpi_dev_get_property(adev, "HotPlugSupportInD3", ACPI_TYPE_INTEGER, &obj) < 0) return false; return obj->integer.value == 1; }