Re: [PATCH v2 5/5] PCI: Set native_pcie_hotplug up front based on pcie_ports_native

[Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 7/14/25 4:00 PM, Sathyanarayanan Kuppuswamy wrote:
>
> On 7/13/25 7:31 AM, Lukas Wunner wrote:
>> Bjorn suggests to "set host->native_pcie_hotplug up front based on
>> CONFIG_HOTPLUG_PCI_PCIE and pcie_ports_native, and pciehp_is_native()
>> would collapse to just an accessor for host->native_pcie_hotplug".
>>
>> Unfortunately only half of this is possible:
>>
>> The check for pcie_ports_native can indeed be moved out of
>> pciehp_is_native() and into acpi_pci_root_create().
>>
>> The check for CONFIG_HOTPLUG_PCI_PCIE however cannot be eliminated:
>>
>> get_port_device_capability() needs to know whether platform firmware has
>> granted PCIe Native Hot-Plug control to the operating system. If it has
>> and CONFIG_HOTPLUG_PCI_PCIE is disabled, the function disables hotplug
>> interrupts in case BIOS left them enabled.
>>
>> If host->native_pcie_hotplug would be set up front based on
>> CONFIG_HOTPLUG_PCI_PCIE, it would later on be impossible for
>> get_port_device_capability() to tell whether it can safely disable hotplug
>> interrupts:  It wouldn't know whether Native Hot-Plug control was granted.
>
> Since pcie_ports_native is a PCI driver specific override option, I am not
> sure it is worth referring to this option in ACPI driver, just to reduce the
> number of pcie_ports_native checks from 2 to 1.
>

Never mind. It looks like the goal is to simplify the pciehp_is_native() call.
Since you cannot get rid of CONFIG_HOTPLUG_PCI_PCIE check, do you
still want to do this simplification?

>
>> Link: https://lore.kernel.org/r/20250627025607.GA1650254@bhelgaas/
>> Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
>> Signed-off-by: Lukas Wunner <lukas@wunner.de>
>> ---
>>   drivers/acpi/pci_root.c    | 3 ++-
>>   drivers/pci/pci-acpi.c     | 3 ---
>>   drivers/pci/pcie/portdrv.c | 2 +-
>>   3 files changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index 74ade4160314..f3de0dc9c533 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -1028,7 +1028,8 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
>>           goto out_release_info;
>>         host_bridge = to_pci_host_bridge(bus->bridge);
>> -    if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
>> +    if (!pcie_ports_native &&
>> +        !(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
>>           host_bridge->native_pcie_hotplug = 0;
>>       if (!(root->osc_control_set & OSC_PCI_SHPC_NATIVE_HP_CONTROL))
>>           host_bridge->native_shpc_hotplug = 0;
>> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
>> index ed7ed66a595b..b513826ea293 100644
>> --- a/drivers/pci/pci-acpi.c
>> +++ b/drivers/pci/pci-acpi.c
>> @@ -820,9 +820,6 @@ bool pciehp_is_native(struct pci_dev *bridge)
>>       if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
>>           return false;
>>   -    if (pcie_ports_native)
>> -        return true;
>> -
>>       host = pci_find_host_bridge(bridge->bus);
>>       return host->native_pcie_hotplug;
>>   }
>> diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
>> index d1b68c18444f..fa83ebdcfecb 100644
>> --- a/drivers/pci/pcie/portdrv.c
>> +++ b/drivers/pci/pcie/portdrv.c
>> @@ -223,7 +223,7 @@ static int get_port_device_capability(struct pci_dev *dev)
>>       if (dev->is_pciehp &&
>>           (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
>>            pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM) &&
>> -        (pcie_ports_native || host->native_pcie_hotplug)) {
>> +        host->native_pcie_hotplug) {
>>           services |= PCIE_PORT_SERVICE_HP;
>>             /*
>
-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer