Re: [Regression] Commit "nvme/pci: Use host managed power state for suspend" has problems

Christoph Hellwig
2019-08-07T10:45:05Z

On Wed, Aug 07, 2019 at 11:48:33AM +0200, Rafael J. Wysocki wrote:
> So I think I know what the problem is here.
>
> If ASPM is disabled for the NVMe device (which is the case on my machine by default),
> skipping the bus-level PM in nvme_suspend() causes the PCIe link of it to stay up and
> that prevents the SoC from getting into deeper package C-states.
>
> If I change the ASPM policy to "powersave" (through the module parameter in there),
> ASPM gets enabled for the NVMe drive and I can get into PC10 via S2Idle with plain 5.3-rc3.
>
> However, that's a bit less than straightforward, so I'm going to post a patch to make
> nvme_suspend() fall back to the "old ways" if ASPM is not enabled for the target device.

Sounds sensibel.

FYI your mail is not properly formatted and has way too long lines.