On Thu, 2012-09-20 at 21:20 +0200, Rafael J. Wysocki wrote: > On Monday, September 17, 2012, Bjorn Helgaas wrote: > > +cc Eric and kexec list > > > > On Mon, Sep 17, 2012 at 2:54 AM, Huang Ying <ying.huang at intel.com> wrote: > > > If PCI devices are put into D3cold before kexec, because the > > > configuration registers of PCI devices in D3cold are not accessible. > > > > > > And if PCI bridges are put into low power state before kexec, > > > configuration registers of PCI devices underneath the PCI bridges are > > > not accessible too. > > > > > > These will make some PCI devices can not be scanned after kexec, so > > > resume the PCI devices in D3cold or PCI bridges in low power state > > > before kexec. > > > > Don't we need to resume the device even without the kexec issue? And > > even if it's in D1 or D2? > > > > It looks to me like pci_msi_shutdown() (and probably drv->shutdown()) > > depend on the device being in D0. > > We should in theory, but we didn't do any power management of PCI bridges > before, so this is the first time we have a problem with it. > > So I'd say, yeah, let's resume if current_state is between D1 and D3cold > inclusive and the kexec comment is not very helpful (the problem is not > kexec-specific in general). Resume from D1 to D3cold for any device or just bridges? Best Regards, Huang Ying > Speaking of kexec, it might consider using the hibernation device freeze > instead of device shutdown (which the kexec jump feature does). I've seen > reports of problems that would be solved this way most likely. > > Thanks, > Rafael > > > > > Signed-off-by: Huang Ying <ying.huang at intel.com> > > > --- > > > drivers/pci/pci-driver.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > --- a/drivers/pci/pci-driver.c > > > +++ b/drivers/pci/pci-driver.c > > > @@ -421,6 +421,10 @@ static void pci_device_shutdown(struct d > > > struct pci_dev *pci_dev = to_pci_dev(dev); > > > struct pci_driver *drv = pci_dev->driver; > > > > > > + /* Resume bridges and devices in D3cold for kexec to work properly */ > > > + if (pci_dev->current_state == PCI_D3cold || pci_dev->subordinate) > > > + pm_runtime_resume(dev); > > > + > > > if (drv && drv->shutdown) > > > drv->shutdown(pci_dev); > > > pci_msi_shutdown(pci_dev); > > > > >
