lkml.org 
[lkml]   [2019]   [Sep]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH] nvme-pci: Save PCI state before putting drive into deepest state
    Date
    On Wednesday, September 18, 2019 11:31:19 PM CEST Rafael J. Wysocki wrote:
    > 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.

    BTW, doing nvme_dev_disable() before nvme_unfreeze() looks odd to me.

    Maybe it would be better to do "unfreeze" and then "disable" in this case?

    >
    > > }
    > > - /*
    > > - * 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;
    > >
    >
    >
    >
    >
    >




    \
     
     \ /
      Last update: 2019-09-18 23:43    [W:2.471 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site