[Intel-wired-lan] [PATCH] fm10k: restore D0 power state upon probe

[Keller, Jacob E]

> -----Original Message-----
> From: Alexander Duyck [mailto:alexander.duyck at gmail.com]
> Sent: Wednesday, June 08, 2016 2:23 PM
> To: Keller, Jacob E <jacob.e.keller at intel.com>
> Cc: Intel Wired LAN <intel-wired-lan at lists.osuosl.org>
> Subject: Re: [Intel-wired-lan] [PATCH] fm10k: restore D0 power state upon
> probe
> 
> On Wed, Jun 8, 2016 at 2:18 PM, Keller, Jacob E
> <jacob.e.keller at intel.com> wrote:
> >> -----Original Message-----
> >> From: Alexander Duyck [mailto:alexander.duyck at gmail.com]
> >> Sent: Wednesday, June 08, 2016 2:02 PM
> >> To: Keller, Jacob E <jacob.e.keller at intel.com>
> >> Cc: Intel Wired LAN <intel-wired-lan at lists.osuosl.org>
> >> Subject: Re: [Intel-wired-lan] [PATCH] fm10k: restore D0 power state
> upon
> >> probe
> >>
> >> On Wed, Jun 8, 2016 at 12:11 PM, Keller, Jacob E
> >> <jacob.e.keller at intel.com> wrote:
> >> >> -----Original Message-----
> >> >> From: Alexander Duyck [mailto:alexander.duyck at gmail.com]
> >> >> Sent: Tuesday, June 07, 2016 8:54 PM
> >> >> To: Keller, Jacob E <jacob.e.keller at intel.com>
> >> >> Cc: Intel Wired LAN <intel-wired-lan at lists.osuosl.org>
> >> >> Subject: Re: [Intel-wired-lan] [PATCH] fm10k: restore D0 power state
> >> upon
> >> >> probe
> >> >>
> >> >> On Tue, Jun 7, 2016 at 5:20 PM, Jacob Keller
> <jacob.e.keller at intel.com>
> >> >> wrote:
> >> >> > It seems that under some circumstances, such as after performing
> an
> >> >> > unbind following an AER injection recovery, the power state of a VF
> >> >> > isn't set to PCI_D0. Following the unbind if we attempt to bind the
> >> >> > device, the MSI-X initialization fails due to incorrect power state.
> >> >>
> >> >> That doesn't make much sense.  I didn't think the VFs had their own
> >> >> power state control.  After all it isn't as if they could switch off
> >> >> while the PF is active on the host.
> >> >>
> >> >> > Fix this by always calling pci_set_power_state(pdev, PCI_D0) on
> driver
> >> >> > device probe.
> >> >>
> >> >> That should be redundant.  There is already code that is called to
> >> >> transition the power state to D0 in pci_enable_device_mem.  As long
> as
> >> >> nobody else has enabled the device it will be ran.
> >> >>
> >> >
> >> > That's weird. In this case, after doing aer-inject on the PF, if we unbind
> >> then bind the VF device, it fails in pci_enable_msix_range which I traced
> into
> >> eventually a call that fails because the state isn't PCI_D0. If I add a
> >> "pci_set_power_state(pdev, PCI_D0)" call in the probe routine it works
> >> fine...?
> >> >
> >> > I don't really know why that'd be the case... thoughts?
> >>
> >> Does the VF even advertise support for PCI power management
> >> capability?  If I recall a VF shouldn't.  As such I think a call to
> >> pci_set_power_state should be returning an error and not doing
> >> anything so I would think this code only has any effect on the PF.  So
> >> I am not certain what this patch is even doing if you aren't reloading
> >> the PF driver to trigger it.
> >>
> >> - Alex
> >
> > I'm not sure either but without it we're ending up with the failure in
> pci_msi_supported failing with -EINVAL because dev->current_state !=
> PCI_D0...
> >
> > It only happens after an unbind of the VF device then a bind. I think
> somehow the dev->current_state gets messed up but I don't know how this
> happens.
> >
> > Thanks,
> > Jake
> 
> When you say unbind/bind are you talking about using the sysfs or is
> this via some other mechanism?
> 
> - Alex

Using sysfs. We echo the PCI address to fm10k's unbind, then echo it to bind.

Thanks,
Jake