Date:   Tue, 6 Aug 2019 03:13:56 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Mario Limonciello <Mario.Limonciello@...l.com>,
        Keith Busch <kbusch@...nel.org>,
        Keith Busch <keith.busch@...el.com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        linux-nvme <linux-nvme@...ts.infradead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rajat Jain <rajatja@...gle.com>
Subject: Re: [Regression] Commit "nvme/pci: Use host managed power state for
 suspend" has problems

at 19:04, Rafael J. Wysocki <rafael@...nel.org> wrote:

> On Fri, Aug 2, 2019 at 12:55 PM Kai-Heng Feng
> <kai.heng.feng@...onical.com> wrote:
>> at 06:26, Rafael J. Wysocki <rafael@...nel.org> wrote:
>>
>>> On Thu, Aug 1, 2019 at 9:05 PM <Mario.Limonciello@...l.com> wrote:
>>>>> -----Original Message-----
>>>>> From: Rafael J. Wysocki <rafael@...nel.org>
>>>>> 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@...onical.com> wrote:
>>>>>> at 06:33, Rafael J. Wysocki <rafael@...nel.org> wrote:
>>>>>>
>>>>>>> On Thu, Aug 1, 2019 at 12:22 AM Keith Busch <kbusch@...nel.org>  
>>>>>>> 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
>>>>>> Rafael’s patch.
>>>>>> But the “real” s2idle power consumption does improve with the patch.
>>>>>
>>>>> Do you mean this patch:
>>>>>
>>>>> https://lore.kernel.org/linux-pm/70D536BE-8DC7-4CA2-84A9-
>>>>> AFB067BA520E@...onical.com/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 doesn’t break HMB Toshiba NVMe I tested. But I think
>>>>>> it’s
>>>>>> 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.
>
> That's the case for me too.
>
>> This happens with or without putting the device to D3.
>
> On my system, though, it only can get to PC3 without putting the NVMe
> into D3 (as reported previously).

I forgot to ask, what BIOS version does the system have?
I don’t see this issue on BIOS v1.5.0.

Kai-Heng

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