On Thu, Sep 19, 2019 at 12:00 AM <mario.limoncie...@dell.com> wrote: > > > -----Original Message----- > > From: Rafael J. Wysocki <r...@rjwysocki.net> > > Sent: Wednesday, September 18, 2019 4:57 PM > > To: Limonciello, Mario > > Cc: kbu...@kernel.org; ax...@fb.com; h...@lst.de; s...@grimberg.me; linux- > > n...@lists.infradead.org; linux-kernel@vger.kernel.org; Hong, Ryan; Wang, > > Crag; s...@google.com; Dominguez, Jared; linux-...@vger.kernel.org; linux- > > p...@vger.kernel.org > > Subject: Re: [PATCH] nvme-pci: Save PCI state before putting drive into > > deepest > > state > > > > > > [EXTERNAL EMAIL] > > > > On Wednesday, September 18, 2019 11:43:28 PM CEST > > mario.limoncie...@dell.com wrote: > > > > -----Original Message----- > > > > From: Rafael J. Wysocki <r...@rjwysocki.net> > > > > Sent: Wednesday, September 18, 2019 4:31 PM > > > > To: Limonciello, Mario > > > > Cc: Keith Busch; Jens Axboe; Christoph Hellwig; Sagi Grimberg; linux- > > > > n...@lists.infradead.org; LKML; Hong, Ryan; Wang, Crag; s...@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.limoncie...@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 > > > > > > > I don't think that pci_load_saved_state() will work, because it sets > > state_saved at the end again (if all goes well). You simply only need to > > clear state_saved here. > > Explicitly calling it with NULL as the saved state to restore seemed to have > that effect > of clearing state (there is an explicit check in there if it's NULL to just > return 0).
Ah, OK, right. I still would rather clear the flag directly, though, as using pci_load_saved_state() for that is just more convoluted. :-)
