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

[Kai-Heng Feng]

at 06:26, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:

> On Thu, Aug 1, 2019 at 9:05 PM <Mario.Limonciello@xxxxxxxx> wrote:
> > > -----Original Message-----
> > > From: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> > > Sent: Thursday, August 1, 2019 12:30 PM
> > > To: Kai-Heng Feng; Keith Busch; Limonciello, Mario
> > > Cc: Keith Busch; Christoph Hellwig; Sagi Grimberg; linux-nvme; Linux  
> > > PM; Linux
> > > Kernel Mailing List; Rajat Jain
> > > Subject: Re: [Regression] Commit "nvme/pci: Use host managed power  
> > > state for
> > > suspend" has problems
> > >
> > >
> > > [EXTERNAL EMAIL]
> > >
> > > On Thu, Aug 1, 2019 at 11:06 AM Kai-Heng Feng
> > > <kai.heng.feng@xxxxxxxxxxxxx> wrote:
> > > > at 06:33, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> > > >
> > > > > On Thu, Aug 1, 2019 at 12:22 AM Keith Busch <kbusch@xxxxxxxxxx> wrote:
> > > > > > On Wed, Jul 31, 2019 at 11:25:51PM +0200, Rafael J. Wysocki wrote:
> > > > > > > A couple of remarks if you will.
> > > > > > >
> > > > > > > First, we don't know which case is the majority at this point.  For
> > > > > > > now, there is one example of each, but it may very well turn out that
> > > > > > > the SK Hynix BC501 above needs to be quirked.
> > > > > > >
> > > > > > > Second, the reference here really is 5.2, so if there are any systems
> > > > > > > that are not better off with 5.3-rc than they were with 5.2, well, we
> > > > > > > have not made progress.  However, if there are systems that are worse
> > > > > > > off with 5.3, that's bad.  In the face of the latest findings the  
> > > > > > > only
> > > > > > > way to avoid that is to be backwards compatible with 5.2 and that's
> > > > > > > where my patch is going.  That cannot be achieved by quirking all
> > > > > > > cases that are reported as "bad", because there still may be
> > > > > > > unreported ones.
> > > > > >
> > > > > > I have to agree. I think your proposal may allow PCI D3cold,
> > > > >
> > > > > Yes, it may.
> > > >
> > > > Somehow the 9380 with Toshiba NVMe never hits SLP_S0 with or without
> > > > Rafaelâs patch.
> > > > But the ârealâ s2idle power consumption does improve with the patch.
> > >
> > > Do you mean this patch:
> > >
> > > https://lore.kernel.org/linux-pm/70D536BE-8DC7-4CA2-84A9-
> > > AFB067BA520E@xxxxxxxxxxxxx/T/#m456aa5c69973a3b68f2cdd4713a1ce83be5145
> > > 8f
> > >
> > > or the $subject one without the above?
> > >
> > > > Can we use a DMI based quirk for this platform? It seems like a platform
> > > > specific issue.
> > >
> > > We seem to see too many "platform-specific issues" here. :-)
> > >
> > > To me, the status quo (ie. what we have in 5.3-rc2) is not defensible.
> > > Something needs to be done to improve the situation.
> >
> > Rafael, would it be possible to try popping out PC401 from the 9380 and  
> > into a 9360 to
> > confirm there actually being a platform impact or not?
>
> Not really, sorry.
>
> > I was hoping to have something useful from Hynix by now before  
> > responding, but oh well.
> >
> > In terms of what is the majority, I do know that between folks at Dell,  
> > Google, Compal,
> > Wistron, Canonical, Micron, Hynix, Toshiba, LiteOn, and Western Digital  
> > we tested a wide
> > variety of SSDs with this patch series.  I would like to think that they  
> > are representative of
> > what's being manufactured into machines now.
>
> Well, what about drives already in the field?  My concern is mostly
> about those ones.
>
> > Notably the LiteOn CL1 was tested with the HMB flushing support and
> > and Hynix PC401 was tested with older firmware though.
> >
> > > > > > In which case we do need to reintroduce the HMB handling.
> > > > >
> > > > > Right.
> > > >
> > > > The patch alone doesnât break HMB Toshiba NVMe I tested. But I think  
> > > > itâs
> > > > still safer to do proper HMB handling.
> > >
> > > Well, so can anyone please propose something specific?  Like an
> > > alternative patch?
> >
> > This was proposed a few days ago:
> > http://lists.infradead.org/pipermail/linux-nvme/2019-July/026056.html
> >
> > However we're still not sure why it is needed, and it will take some  
> > time to get
> > a proper failure analysis from LiteOn  regarding the CL1.
>
> Thanks for the update, but IMO we still need to do something before
> final 5.3 while the investigation continues.
>
> Honestly, at this point I would vote for going back to the 5.2
> behavior at least by default and only running the new code on the
> drives known to require it (because they will block PC10 otherwise).
>
> Possibly (ideally) with an option for users who can't get beyond PC3
> to test whether or not the new code helps them.

I just found out that the XPS 9380 at my hand never reaches SLP_S0 but only  
PC10.
This happens with or without putting the device to D3.

Kai-Heng