On Fri, Dec 15, 2017 at 7:30 PM, Bjorn Helgaas <helg...@kernel.org> wrote: > On Fri, Dec 15, 2017 at 03:07:18AM +0100, Rafael J. Wysocki wrote: >> From: Rafael J. Wysocki <rafael.j.wyso...@intel.com> >> >> It is incorrect to call pci_restore_state() for devices in low-power >> states (D1-D3), as that involves the restoration of MSI setup which >> requires MMIO to be operational and that is only the case in D0. >> >> However, pci_pm_thaw_noirq() may do that if the driver's "freeze" >> callbacks put the device into a low-power state, so fix it by making >> it force devices into D0 via pci_set_power_state() instead of trying >> to "update" their power state which is pointless. >> >> Fixes: e60514bd4485 (PCI/PM: Restore the status of PCI devices across >> hibernation) >> Cc: 4.13+ <sta...@vger.kernel.org> # 4.13+ >> Reported-by: Thomas Gleixner <t...@linutronix.de> >> Reported-by: Maarten Lankhorst <d...@mblankhorst.nl> >> Tested-by: Thomas Gleixner <t...@linutronix.de> >> Tested-by: Maarten Lankhorst <d...@mblankhorst.nl> >> Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com> > > Acked-by: Bjorn Helgaas <bhelg...@google.com> > > Let me know if you want me to take this. I don't have anything > currently queued up that touches pci-driver.c, so I'm happy if you > take it yourself.
I will take it. Depending of what Yu finds, we may need an additional fix to make the Purley system work. >> --- >> >> The bug is not as old as I thought, actually. >> >> Yes, we did the pci_update_current_state() in pci_pm_thaw_noirq() >> forever, but it started to be problematic in 4.13, when we started >> to call pci_restore_state() in addition to it to fix another issue. >> >> --- >> drivers/pci/pci-driver.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> Index: linux-pm/drivers/pci/pci-driver.c >> =================================================================== >> --- linux-pm.orig/drivers/pci/pci-driver.c >> +++ linux-pm/drivers/pci/pci-driver.c >> @@ -1027,7 +1027,12 @@ static int pci_pm_thaw_noirq(struct devi >> if (pci_has_legacy_pm_support(pci_dev)) >> return pci_legacy_resume_early(dev); >> >> - pci_update_current_state(pci_dev, PCI_D0); >> + /* >> + * pci_restore_state() requires the device to be in D0 (because of MSI >> + * restoration among other things), so force it into D0 in case the >> + * driver's "freeze" callbacks put it into a low-power state directly. >> + */ >> + pci_set_power_state(pci_dev, PCI_D0); >> pci_restore_state(pci_dev); >> >> if (drv && drv->pm && drv->pm->thaw_noirq) >>
