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.
