linux-kernel - Re: [PATCH] nvme-pci: Shutdown the device if D3Cold is allowed by the user

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Message-ID: <CAJZ5v0gUpDw_NjTDtHGCUnKK0C+x0nrW6mP0tHQoXsgwR2RH8g@mail.gmail.com>
Date: Fri, 13 Dec 2024 15:35:15 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Christoph Hellwig <hch@....de>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, 
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, Bjorn Helgaas <helgaas@...nel.org>, kbusch@...nel.org, 
	axboe@...nel.dk, sagi@...mberg.me, linux-nvme@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, andersson@...nel.org, 
	konradybcio@...nel.org, Len Brown <len.brown@...el.com>, linux-pm@...r.kernel.org, 
	"Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] nvme-pci: Shutdown the device if D3Cold is allowed by the user

On Thu, Dec 12, 2024 at 4:14 PM Christoph Hellwig <hch@....de> wrote:
>
> On Thu, Dec 12, 2024 at 01:49:15PM +0100, Ulf Hansson wrote:
> > Right. This seems to somewhat work for ACPI types of systems, because
> > ACPI is controlling the low power state for all the devices. Based on
> > the requested system wide low power state, ACPI can then decide to
> > call pm_set_suspend_via_firmware() or not.
> >
> > Still there is a problem with this for ACPI too.
> >
> > How does ACPI know whether it's actually a good idea to keep the NVMe
> > storage powered in s2idle (ACPI calls pm_set_suspend_via_firmware()
> > only for S2R and S2disk!?)? Especially when my laptop only supports
> > s2idle and that's what I will use when I close the lid. In this way,
> > the NMVe storage will certainly contribute to draining the battery,
> > especially when I won't be using my laptop for a couple of days.
> >
> > In my opinion, we need a better approach that is both flexible and
> > that dynamically adjusts based upon the use case.
>
> Agreed.  I'd be happy to work with the PM maintainers to do this,
> but I don't really know enough about the PM core to drive it
> (as the reply from Rafael to my mail makes pretty clear :))

I'm here to help.

Let me know what exactly you want to achieve and we'll see how to make it work.