From: "David E. Box" <david.e.box@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: axboe@fb.com, sagi@grimberg.me, linux-acpi@vger.kernel.org,
linux-pci@vger.kernel.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
shyjumon.n@intel.com, kbusch@kernel.org, bhelgaas@google.com,
dan.j.williams@intel.com, hch@lst.de, lenb@kernel.org
Subject: Re: [PATCH V2 1/2] PCI: Add ACPI StorageD3Enable _DSD support
Date: Wed, 24 Jun 2020 15:09:33 -0700 [thread overview]
Message-ID: <e980bc2959b5a959bddfa63adb35aeae8261ab06.camel@linux.intel.com> (raw)
In-Reply-To: <20200624213757.GA2591059@bjorn-Precision-5520>
On Wed, 2020-06-24 at 16:37 -0500, Bjorn Helgaas wrote:
> On Fri, Jun 12, 2020 at 01:48:19PM -0700, David E. Box wrote:
> > StorageD3Enable is a boolean property that indicates that the
> > platform
> > wants to use D3 for PCIe storage drives during suspend-to-idle.
>
> Is this something that should apply to plug-in drives, or does this
> only apply to soldered-in things?
>
> > It is a
> > BIOS work around that is currently in use on shipping systems like
> > some
> > Intel Comet Lake platforms.
>
> What is this BIOS work around? Is there a defect here that's being
> worked around? What's the defect?
>
> > It is meant to change default driver policy for
> > suspend that may cause higher power consumption.
>
> I guess this means that by changing the driver policy from the
> default, we can save some power?
Yes. Maybe 'work around' was a poor choice of words. 'Getting around
default driver policy' is the issue. There is no hardware defect. One
of the uses of the suspend-to-idle flow is to support compliance with
increasingly tighter energy regulations. One of the ways to do this on
desktop systems is to power off the ATX power supply during s2idle and
use the 5V standby rail for self refresh and other low power needs. But
the platforms that support this can't shutdown the PS unless PCI ports
are placed in D3. On Linux this won't happen with NVMe drives because
the default driver policy is to use ASPM (NVMe APST) during s2idle.
Windows has a related concern. So to 'get around' the driver choosing a
policy that will result in higher power consumption, they implemented
this _DSD to inform the OS of its preference for D3 on the PCI port.
David
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next prev parent reply other threads:[~2020-06-24 22:09 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 0:32 [PATCH 0/2] Add support for StorageD3Enable _DSD property David E. Box
2020-04-28 0:32 ` [PATCH 1/2] pci: Add ACPI StorageD3Enable _DSD support David E. Box
2020-05-18 12:34 ` Rafael J. Wysocki
2020-05-19 17:10 ` David E. Box
2020-04-28 0:32 ` [PATCH 2/2] drivers/nvme: Add support for ACPI StorageD3Enable property David E. Box
2020-04-28 5:13 ` [PATCH 0/2] Add support for StorageD3Enable _DSD property Christoph Hellwig
2020-04-28 14:09 ` David E. Box
2020-04-28 14:22 ` Christoph Hellwig
2020-04-28 15:27 ` David E. Box
2020-04-29 5:20 ` Williams, Dan J
2020-04-29 15:10 ` Keith Busch
2020-04-29 16:11 ` David E. Box
2020-05-01 13:12 ` hch
2020-05-01 15:54 ` David E. Box
2020-05-01 13:10 ` hch
2020-05-18 13:51 ` David Woodhouse
2020-05-18 17:20 ` Dan Williams
2020-06-12 20:48 ` [PATCH V2 0/2] nvme: Add support for ACPI StorageD3Enable property David E. Box
2020-06-24 18:55 ` David E. Box
2020-06-24 19:10 ` Dan Williams
2020-06-24 19:39 ` David E. Box
2020-07-02 22:50 ` [PATCH v4] drivers/nvme: " David E. Box
2020-07-06 14:57 ` Rafael J. Wysocki
2020-07-07 21:24 ` David E. Box
2020-07-07 7:09 ` Christoph Hellwig
2020-07-09 18:43 ` [PATCH V5] " David E. Box
2020-07-13 11:12 ` Rafael J. Wysocki
2020-07-16 14:39 ` Christoph Hellwig
2021-05-26 19:25 ` Raul E Rangel
2020-06-12 20:48 ` [PATCH V2 1/2] PCI: Add ACPI StorageD3Enable _DSD support David E. Box
2020-06-24 21:15 ` Bjorn Helgaas
2020-06-25 11:30 ` Rafael J. Wysocki
2020-06-25 12:16 ` Mika Westerberg
2020-06-25 17:30 ` Bjorn Helgaas
2020-06-24 21:37 ` Bjorn Helgaas
2020-06-24 22:09 ` David E. Box [this message]
2020-06-12 20:48 ` [PATCH V2 2/2] drivers/nvme: Add support for ACPI StorageD3Enable property David E. Box
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