Re: [PATCH v8 2/5] ACPI/PCI: Ignore _OSC negotiation result if pcie_ports_native is set.

Bjorn Helgaas
2020-09-15T22:20:55Z

On Sun, Sep 13, 2020 at 01:54:38PM -0700, Kuppuswamy, Sathyanarayanan wrote:
> On 9/10/20 1:14 PM, Bjorn Helgaas wrote:
> > On Fri, Jul 24, 2020 at 08:58:53PM -0700, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> > > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> > >
> > > pcie_ports_native is set only if user requests native handling
> > > of PCIe capabilities via pcie_port_setup command line option.
> > > User input takes precedence over _OSC based control negotiation
> > > result. So consider the _OSC negotiated result only if
> > > pcie_ports_native is unset.
> > >
> > > Also, since struct pci_host_bridge ->native_* members caches the
> > > ownership status of various PCIe capabilities, use them instead
> > > of distributed checks for pcie_ports_native.
> > >
> > > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> > > ---
> > > drivers/acpi/pci_root.c | 61 ++++++++++++++++++++++++++-----
> > > drivers/pci/hotplug/pciehp_core.c | 2 +-
> > > drivers/pci/pci-acpi.c | 3 --
> > > drivers/pci/pcie/aer.c | 2 +-
> > > drivers/pci/pcie/portdrv_core.c | 9 ++---
> > > 5 files changed, 56 insertions(+), 21 deletions(-)
> > >
> > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > > index f90e841c59f5..f8981d4e044d 100644
> > > --- a/drivers/acpi/pci_root.c
> > > +++ b/drivers/acpi/pci_root.c
> > > @@ -145,6 +145,17 @@ static struct pci_osc_bit_struct pci_osc_control_bit[] = {
> > > { OSC_PCI_EXPRESS_DPC_CONTROL, "DPC" },
> > > };
>
> > > + else
> > > + dev_warn(&bus->dev, "OS overrides %s firmware control",
> > > + get_osc_desc(OSC_PCI_EXPRESS_NATIVE_HP_CONTROL));
> >
> > There's got to be a way to write this more concisely. Maybe something
> > like this?
> >
> > #define OSC_OWNER(ctrl, bit, flag) \
> > if (!(ctrl & bit)) \
> > flag = 0;
> >
> > if (pcie_ports_native)
> > decode_osc_control(root, "OS forcibly taking over", ~0);
>
> BIT1 and BIT6 does not have PCIe dependency. And BIT7-31 are reserved.
> So we can't force all _OSC bits based on pcie_ports_native value.
> So, IM0, its better to handle PCIe features seperatly.

Yes, we may need to handle a few bits specially. But we need to
figure out a nicer-looking way of coding this. It's too cumbersome to
check pcie_ports_native and log a message for every _OSC bit
individually.

> > else {
> > ctrl = root->osc_control_set;
> > OSC_OWNER(ctrl, OSC_PCI_EXPRESS_AER_CONTROL, host_bridge->native_aer);
> > OSC_OWNER(ctrl, OSC_PCI_EXPRESS_PME_CONTROL, host_bridge->native_pme);
> > ...
> > }
>
>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer