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

[Kuppuswamy, Sathyanarayanan]

On 9/10/20 1:14 PM, Bjorn Helgaas wrote:
> On Fri, Jul 24, 2020 at 08:58:53PM -0700, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
> > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxxx>
> > ---
> >   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.
>    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