Hi Bjorn, On Tue, May 24, 2016 at 07:23:57AM -0500, Bjorn Helgaas wrote: > On Mon, May 23, 2016 at 04:50:15PM -0500, Bjorn Helgaas wrote: > > [+cc Valdis, Dave] > > > > On Mon, May 23, 2016 at 03:00:42PM -0500, Bjorn Helgaas wrote: > > > On Mon, May 23, 2016 at 11:20:48AM +0300, Mika Westerberg wrote: > > > > When a PCI device is removed through sysfs interface the upstream bridge > > > > (PCIe port) can be runtime suspended if it was the last device on that bus. > > > > Now, if the bridge is in D3 we cannot find devices below the bridge > > > > anymore. For example following fails to find the removed device again: > > > > > > > > # echo 1 > /sys/bus/pci/devices/0000:00:01.0/0000:01:00.0/remove > > > > # echo 1 > /sys/bus/pci/devices/0000:00:01.0/rescan > > > > > > > > Where 0000:00:01.0 is the bridge device. > > > > > > > > In order to be able to rescan devices below the bridge add > > > > pm_runtime_get_sync()/pm_runtime_put() calls to pci_scan_bridge(). This > > > > should keep bridges powered on while their children devices are being > > > > scanned. > > > > > > > > Reported-by: Peter Wu <peter@xxxxxxxxxxxxx> > > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > > > > This looks like basically the same idea as "ACPI / hotplug / PCI: > > > Runtime resume bridge before rescan". > > > > > > The hotplug_event() path modified by that patch eventually calls > > > pci_scan_bridge(): > > > > > > hotplug_event > > > enable_slot > > > pci_scan_bridge > > > > > > so this patch looks a little more general. Does it make "ACPI / > > > hotplug / PCI: Runtime resume bridge before rescan" unnecessary? > > > Can I just replace that patch with this one? > > > > I speculatively replaced "ACPI / hotplug / PCI: Runtime resume bridge > > before rescan" with this one and pushed the result to > > > > https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/log/?h=pci/pm > > > > Please take a look, test it, and let me know if I need to add the ACPI > > patch back. > > > > This branch also includes the fix for the lockdep splat reported by > > Valdis. This is what I hope to get into v4.7-rc1. > > Ping? I'd like to ask Linus to pull this pci/pm branch before v4.7-rc1. > It currently has these changes: > > 8b71f5652eea PCI: Add runtime PM support for PCIe ports > af81f0fa638b PCI: Power on bridges before scanning new devices > 9741a01c9f55 PCI: Put PCIe ports into D3 during suspend > b3a63ff7baf1 PCI: Don't clear d3cold_allowed for PCIe ports > > I dropped "ACPI / hotplug / PCI: Runtime resume bridge before rescan" > on the assumption that "PCI: Power on bridges before scanning new > devices" is sufficient to cover both the ACPI and the generic PCi > rescan cases, but I'd like some reassurance about that. > > Lukas, you tested that acpiphp patch. Would you be able to verify > that your test case still works even with that patch replaced by the > generic one? I only have a Mac and Macs don't use ACPI-based hotplug, only native pciehp hotplug. So unfortunately I can't say anything about whether the ACPI patch is still needed. For Dave Airlie's use case the patch seems not to be needed, he wants to suspend root ports to which a GPU is attached, so I guess he doesn't care much about hotplug. The patch could therefore be pulled by Linus separately, if it turns that it's still needed. Thanks, Lukas > > FWIW, my pci/pm branch with these updates is included in > next-20160524. > > > > > --- > > > > drivers/pci/probe.c | 9 +++++++++ > > > > 1 file changed, 9 insertions(+) > > > > > > > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > > > > index 8004f67c57ec..15e77c92311e 100644 > > > > --- a/drivers/pci/probe.c > > > > +++ b/drivers/pci/probe.c > > > > @@ -16,6 +16,7 @@ > > > > #include <linux/aer.h> > > > > #include <linux/acpi.h> > > > > #include <linux/irqdomain.h> > > > > +#include <linux/pm_runtime.h> > > > > #include "pci.h" > > > > > > > > #define CARDBUS_LATENCY_TIMER 176 /* secondary latency timer */ > > > > @@ -832,6 +833,12 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass) > > > > u8 primary, secondary, subordinate; > > > > int broken = 0; > > > > > > > > + /* > > > > + * Make sure the bridge is powered on to be able to access config > > > > + * space of devices below it. > > > > + */ > > > > + pm_runtime_get_sync(&dev->dev); > > > > + > > > > pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses); > > > > primary = buses & 0xFF; > > > > secondary = (buses >> 8) & 0xFF; > > > > @@ -1012,6 +1019,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass) > > > > out: > > > > pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl); > > > > > > > > + pm_runtime_put(&dev->dev); > > > > + > > > > return max; > > > > } > > > > EXPORT_SYMBOL(pci_scan_bridge); > > > > -- > > > > 2.8.1 > > > > > > > > -- > > > > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > > > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
