From: <Mario.Limonciello@dell.com>
To: <rjw@rjwysocki.net>
Cc: <kbusch@kernel.org>, <axboe@fb.com>, <hch@lst.de>,
<sagi@grimberg.me>, <linux-nvme@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <Ryan.Hong@Dell.com>,
<Crag.Wang@dell.com>, <sjg@google.com>,
<Jared.Dominguez@dell.com>, <linux-pci@vger.kernel.org>,
<linux-pm@vger.kernel.org>
Subject: RE: [PATCH] nvme-pci: Save PCI state before putting drive into deepest state
Date: Wed, 18 Sep 2019 21:43:28 +0000 [thread overview]
Message-ID: <346fd9ced98e40229d0cc0871ad5ed32@AUSX13MPC105.AMER.DELL.COM> (raw)
In-Reply-To: <4858057.cjDlXVALXj@kreacher>
> -----Original Message-----
> From: Rafael J. Wysocki <rjw@rjwysocki.net>
> Sent: Wednesday, September 18, 2019 4:31 PM
> To: Limonciello, Mario
> Cc: Keith Busch; Jens Axboe; Christoph Hellwig; Sagi Grimberg; linux-
> nvme@lists.infradead.org; LKML; Hong, Ryan; Wang, Crag; sjg@google.com;
> Dominguez, Jared; Linux PCI; Linux PM
> Subject: Re: [PATCH] nvme-pci: Save PCI state before putting drive into deepest
> state
>
>
> [EXTERNAL EMAIL]
>
> On Thursday, September 12, 2019 1:42:33 AM CEST Mario Limonciello wrote:
> > The action of saving the PCI state will cause numerous PCI configuration
> > space reads which depending upon the vendor implementation may cause
> > the drive to exit the deepest NVMe state.
> >
> > In these cases ASPM will typically resolve the PCIe link state and APST
> > may resolve the NVMe power state. However it has also been observed
> > that this register access after quiesced will cause PC10 failure
> > on some device combinations.
> >
> > To resolve this, move the PCI state saving to before SetFeatures has been
> > called. This has been proven to resolve the issue across a 5000 sample
> > test on previously failing disk/system combinations.
>
> This sounds reasonable to me, but it would be nice to CC that to linux-pm
> and/or linux-pci too.
>
> > Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
> > ---
> > drivers/nvme/host/pci.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> > index 732d5b6..9b3fed4 100644
> > --- a/drivers/nvme/host/pci.c
> > +++ b/drivers/nvme/host/pci.c
> > @@ -2894,6 +2894,13 @@ static int nvme_suspend(struct device *dev)
> > if (ret < 0)
> > goto unfreeze;
> >
> > + /*
> > + * A saved state prevents pci pm from generically controlling the
> > + * device's power. If we're using protocol specific settings, we don't
> > + * want pci interfering.
> > + */
> > + pci_save_state(pdev);
> > +
> > ret = nvme_set_power_state(ctrl, ctrl->npss);
> > if (ret < 0)
> > goto unfreeze;
> > @@ -2908,12 +2915,6 @@ static int nvme_suspend(struct device *dev)
>
> This is the case in which the PCI layer is expected to put the device into
> D3, so you need
>
> pdev->state_saved = 0;
>
> at this point, because you have saved the config space already.
>
> > ret = 0;
> > goto unfreeze;
>
> And here you don't need to jump to "unfreeze" any more.
>
> > }
> > - /*
> > - * A saved state prevents pci pm from generically controlling the
> > - * device's power. If we're using protocol specific settings, we don't
> > - * want pci interfering.
> > - */
> > - pci_save_state(pdev);
> > unfreeze:
> > nvme_unfreeze(ctrl);
> > return ret;
> >
>
>
>
Thanks, I actually followed up with something along that line in a v2 sent out
today. My apology you weren't in CC, but here is a weblink to it.
http://lists.infradead.org/pipermail/linux-nvme/2019-September/027251.html
next prev parent reply other threads:[~2019-09-18 21:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 23:42 [PATCH] nvme-pci: Save PCI state before putting drive into deepest state Mario Limonciello
2019-09-17 21:24 ` Keith Busch
2019-09-17 21:35 ` Rafael J. Wysocki
2019-09-18 16:52 ` Mario.Limonciello
2019-09-18 21:27 ` Rafael J. Wysocki
2019-09-18 17:28 ` Keith Busch
2019-09-18 21:31 ` Rafael J. Wysocki
2019-09-18 21:42 ` Rafael J. Wysocki
2019-09-18 21:43 ` Mario.Limonciello [this message]
2019-09-18 21:57 ` Rafael J. Wysocki
2019-09-18 22:00 ` Mario.Limonciello
2019-09-18 22:03 ` Rafael J. Wysocki
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