Re: [PATCH v1 2/4] ACPI: PCI: Introduce acpi_dev_get_pci_dev()

[Andy Shevchenko]

On Wed, Jul 15, 2026 at 05:16:19PM +0200, Rafael J. Wysocki wrote:

> Some acpi_get_pci_dev() callers already have a struct ACPI device for
> which they want to get the struct pci_dev pointer of the associated
> PCI device, so they don't need to look for one.
> 
> For this reason, add acpi_dev_get_pci_dev() that will get a PCI device
> for a given ACPI one (if possible) and turn acpi_get_pci_dev() into
> a static inline helper passing the acpi_fetch_acpi_dev() return value
> directly to acpi_dev_get_pci_dev().

...

>  /**
> - * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
> - * @handle: the handle in question
> + * acpi_dev_get_pci_dev - Get a struct pci_dev for a given ACPI device
> + * @adev: Target ACPI device.
>   *
> - * Given an ACPI CA handle, the desired PCI device is located in the
> - * list of PCI devices.
> + * Get the first PCI device associated with @adev, if present, and bump up its

What is the meaning of the "first PCI device" in terms of ACPI specification (and
implementation in the Linux kernel)? I think it's impossible case to have more
than one object to be a companion to a PCI device. Am I wrong?

> + * reference counter.
>   *
> - * If the device is found, its reference count is increased and this
> - * function returns a pointer to its data structure.  The caller must
> - * decrement the reference count by calling pci_dev_put().
> - * If no device is found, %NULL is returned.
> + * Callers are responsible for dropping the PCI device reference obtained by
> + * this function.
> + *
> + * Return: The struct pci_dev pointer of a reference-counted PCI device on
> + * success or NULL on failure.
>   */

-- 
With Best Regards,
Andy Shevchenko