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

Kuppuswamy, Sathyanarayanan
2020-09-13T20:54:45Z

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.
> 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