[PATCH] nvme-pci: Avoid to go into d3cold if device can't use npss.

[Kai-Heng Feng]

On Wed, May 26, 2021 at 10:49 AM Keith Busch <kbusch at kernel.org> wrote:
>
> On Wed, May 26, 2021 at 10:02:27AM +0800, Koba Ko wrote:
> > On Tue, May 25, 2021 at 3:44 PM Christoph Hellwig <hch at lst.de> wrote:
> > >
> > > On Thu, May 20, 2021 at 11:33:15AM +0800, Koba Ko wrote:
> > > > After resume, host can't change power state of the closed controller
> > > > from D3cold to D0.
> > >
> > > Why?
> > As per Kai-Heng said, it's a regression introduced by commit
> > b97120b15ebd ("nvme-pci:
> > use simple suspend when a HMB is enabled"). The affected NVMe is using HMB.
>
> That really doesn't add up. The mentioned commit restores the driver
> behavior for HMB drives that existed prior to d916b1be94b6d from kernel
> 5.3. Is that NVMe device broken in pre-5.3 kernels, too?

Quite likely. The system in question is a late 2020 Ice Lake laptop,
so it was released after 5.3 kernel.

Kai-Heng