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

[Christoph Hellwig <hch@lst.de>]

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 :))