On Thursday, May 17, 2018 4:13:24 PM CEST Bjorn Helgaas wrote:
> On Thu, May 17, 2018 at 12:28:54PM +0300, Mika Westerberg wrote:
> > Currently we request control of native PCIe hotplug unconditionally.
> > That may cause problems because native PCIe hotplug events are handled
> > by pciehp driver and if it is not enabled those events will be lost.
> > Make this bit more robust and request control of native PCIe hotplug
> > only if we are actually prepared to do so (pciehp driver is enabled).
> >
> > While there rename host->native_hotplug to host->native_pcie_hotplug
> > because we do the same for SHPC hotplug in subsequent patches.
> >
> > Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > ---
> > drivers/acpi/pci_root.c | 6 ++++--
> > drivers/pci/pcie/portdrv_core.c | 2 +-
> > drivers/pci/probe.c | 2 +-
> > include/linux/pci.h | 2 +-
> > 4 files changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index 0da18bde6a16..02ab96f00952 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -29,6 +29,7 @@
> > #include <linux/pci.h>
> > #include <linux/pci-acpi.h>
> > #include <linux/pci-aspm.h>
> > +#include <linux/pci_hotplug.h>
> > #include <linux/dmar.h>
> > #include <linux/acpi.h>
> > #include <linux/slab.h>
> > @@ -472,9 +473,10 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
> > }
> >
> > control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
> > - | OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
> > | OSC_PCI_EXPRESS_PME_CONTROL;
> >
> > + if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
> > + control |= OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;
> > if (pci_aer_available()) {
> > if (aer_acpi_firmware_first())
> > dev_info(&device->dev,
> > @@ -900,7 +902,7 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
> >
> > host_bridge = to_pci_host_bridge(bus->bridge);
> > if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
> > - host_bridge->native_hotplug = 0;
> > + host_bridge->native_pcie_hotplug = 0;
> > if (!(root->osc_control_set & OSC_PCI_EXPRESS_AER_CONTROL))
> > host_bridge->native_aer = 0;
> > if (!(root->osc_control_set & OSC_PCI_EXPRESS_PME_CONTROL))
>
> Rafael, I noticed that the PCI Firmware Spec, r3.2, sec 4.5.2.2, says
> we're required to evaluate _OSC when resuming from S4. I don't see a
> path where we do that today.
No, we don't do that today.
> Am I missing it? If not, what resume hook do we need to use to do
> this?
We could do that in the ->restore_noirq callback of the host bridge
device I suppose. Basically, before resuming all of the PCI devices
on the bus.
However, question is on what conditions. Do the previous versions of the
spec have this requirement or is it just a new thing?
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