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 7/13/25 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.

> 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