forked from Minki/linux
df4f9bc4fb
This patch implements a solution for a BIOS hack used on some currently shipping Intel systems to change driver power management policy for PCIe NVMe drives. Some newer Intel platforms, like some Comet Lake systems, require that PCIe devices use D3 when doing suspend-to-idle in order to allow the platform to realize maximum power savings. This is particularly needed to support ATX power supply shutdown on desktop systems. In order to ensure this happens for root ports with storage devices, Microsoft apparently created this ACPI _DSD property as a way to influence their driver policy. To my knowledge this property has not been discussed with the NVME specification body. Though the solution is not ideal, it addresses a problem that also affects Linux since the NVMe driver's default policy of using NVMe APST during suspend-to-idle prevents the PCI root port from going to D3 and leads to higher power consumption for these platforms. The power consumption difference may be negligible on laptop systems, but many watts on desktop systems when the ATX power supply is blocked from powering down. The patch creates a new nvme_acpi_storage_d3 function to check for the StorageD3Enable property during probe and enables D3 as a quirk if set. It also provides a 'noacpi' module parameter to allow skipping the quirk if needed. Tested with: - PM961 NVMe SED Samsung 512GB - INTEL SSDPEKKF512G8 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@linux.intel.com> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de> |
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