On Mon, 2020-05-18 at 14:34 +0200, Rafael J. Wysocki wrote: > On Tuesday, April 28, 2020 2:32:13 AM CEST David E. Box wrote: > > NVMe storage power management during suspend-to-idle, particularly > > on > > laptops, has been inconsistent with some devices working with D3 > > while > > others must rely on NVMe APST in order for power savings to be > > realized. > > Currently the default is to use APST unless quirked to do > > otherwise. > > However newer platforms, like Intel Comet Lake systems, may require > > NVMe > > drives to use D3 in order for the PCIe ports to be properly power > > managed. > > To make it easier for drivers to choose, these platforms may supply > > a > > special "StorageD3Enable" _DSD property under the root port that > > the device > > is attached to. If supplied, the driver must use D3 in order for > > the > > platform to realize the deepest power savings in suspend-to-idle. > > > > Adds support for the _DSD to the pci/acpi layer. > > > > Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx> > > Link: > > https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/power-management-for-storage-hardware-devices-intro > > Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx> > > --- > > drivers/acpi/property.c | 3 +++ > > drivers/pci/pci-acpi.c | 47 > > +++++++++++++++++++++++++++++++++++++++++ > > drivers/pci/pci.c | 6 ++++++ > > drivers/pci/pci.h | 4 ++++ > > include/linux/pci.h | 1 + > > 5 files changed, 61 insertions(+) > > > > diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c > > index e601c4511a8b..f09375ab40e4 100644 > > --- a/drivers/acpi/property.c > > +++ b/drivers/acpi/property.c > > @@ -45,6 +45,9 @@ static const guid_t prp_guids[] = { > > /* Thunderbolt GUID for WAKE_SUPPORTED: 6c501103-c189-4296- > > ba72-9bf5a26ebe5d */ > > GUID_INIT(0x6c501103, 0xc189, 0x4296, > > 0xba, 0x72, 0x9b, 0xf5, 0xa2, 0x6e, 0xbe, 0x5d), > > + /* D3 Support for storage devivce: 5025030f-842f-4ab4-a561- > > 99a5189762d0 */ > > + GUID_INIT(0x5025030f, 0x842f, 0x4ab4, > > + 0xa5, 0x61, 0x99, 0xa5, 0x18, 0x97, 0x62, 0xd0), > > }; > > > > /* ACPI _DSD data subnodes GUID: dbb8e3e6-5886-4ba6-8795- > > 1319f52a966b */ > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > > index d21969fba6ab..5df249ebf022 100644 > > --- a/drivers/pci/pci-acpi.c > > +++ b/drivers/pci/pci-acpi.c > > @@ -972,6 +972,52 @@ static bool acpi_pci_bridge_d3(struct pci_dev > > *dev) > > return val == 1; > > } > > > > +static bool acpi_pci_storage_d3(struct pci_dev *dev) > > +{ > > + const struct fwnode_handle *fwnode; > > + struct acpi_device *adev; > > + struct pci_dev *root; > > + acpi_handle handle; > > + acpi_status status; > > + u8 val; > > + > > + /* > > + * Look for _DSD property specifying that the storage device on > > + * the port must use D3 to support deep platform power savings > > during > > + * suspend-to-idle > > + */ > > + root = pci_find_pcie_root_port(dev); > > + if (!root) > > + return false; > > + > > + 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); > > + } > > + > > + if (!adev) > > + return false; > > + > > + status = acpi_get_handle(adev->handle, "PXSX", &handle); > > + if (ACPI_FAILURE(status)) > > + return false; > > + > > + adev = acpi_bus_get_acpi_device(handle); > > + if (!adev) > > + return false; > > + > > + fwnode = acpi_fwnode_handle(adev); > > + if (!fwnode_property_read_u8(fwnode, "StorageD3Enable", &val)) > > + return val == 1; > > + > > + return false; > > +} > > Kind of orthogonal to what happens to the second patch in this > series, I don't > think that the PCI changes below are all needed. > > IMO it would be sufficient to export the function above, maybe as > pci_acpi_storage_d3(), to drivers, so that they can call it directly > as > desired. > > Since _DSD return data are not allowed by the spec to change between > subsequent invocations of it, the interested driver may call this > function > once at the device init time and quirk it accordingly if needed. Yeah this is better. Will do. Thanks.
