Re: [PATCH v6 19/23] ata: libata-core: Do not resume runtime suspended ports

[Damien Le Moal <dlemoal@kernel.org>]

On 2023/09/25 19:26, Phillip Susi wrote:
> 
> Damien Le Moal <dlemoal@kernel.org> writes:
> 
>> The scsi disk driver does not resume disks that have been runtime
>> suspended by the user. To be consistent with this behavior, do the same
>> for ata ports and skip the PM request in ata_port_pm_resume() if the
>> port was already runtime suspended. With this change, it is no longer
>> necessary to force the PM state of the port to ACTIVE as the PM core
>> code will take care of that when handling runtime resume.
> 
> The problem with this is that ATA disks normally spin up on their own
> after system resume.  As a result, if the disk was put to sleep with
> runtime pm before the system suspend, then after resume, the kernel will
> still show that it is runtime suspended, even though it is not.  Then
> the disk will keep spinning forever.

I suspect you are talking about resume from hybernation here, where the drive
may have been completely powered off... Yes, in such case, the drive will
spinup, unless you have PUIS and enabled it.

> We need to check the drive on system resume to see if it is in standby
> or not, and force the runtime pm state to match.  I couldn't quite work
> out how to do that properly before.  I dug up my old patch series and
> have been reviewing it.  If you are interested, it can be found here:
> 
> https://lore.kernel.org/all/1387236657-4852-5-git-send-email-psusi@ubuntu.com/

Sure, but please do not have this delay this patch series. The problem you are
describing above exists today already. This patch series is not making it worse,
nor is it trying to solve it. And note that this issue is not just for ATA. SCSI
devices locally attached to a machine that you hybernate will end up doing the
same and spinup when power is restored...

-- 
Damien Le Moal
Western Digital Research