Re: [PATCH v3 4/5] PCI: Add pci_irq_type() to query the allocated interrupt type

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Missing dummy implementation of pci_irq_type() for !CONFIG_PCI configurations
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--- Patch [4]: [PATCH v3 4/5] PCI: Add pci_irq_type() to query the allocated interrupt type ---
commit dc3ae5a104b31d99bffe0b8a2992cb68e0130731
Author: Danilo Krummrich <[email protected]>

PCI: Add pci_irq_type() to query the allocated interrupt type

This patch adds a helper function to return the interrupt type (MSI-X, MSI,
or INTX) that the PCI core selected after a successful call to
pci_alloc_irq_vectors(). It provides a common way for drivers to query this
information without directly accessing the pci_dev bitfields.

Link: https://elixir.bootlin.com/linux/v7.1/source/drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c#L196 [1]
Link: https://lore.kernel.org/all/[email protected]/ [2]

> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 64b308b6e61c1..80b8561b5be0b 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
[ ... ]
> @@ -1845,6 +1865,11 @@ static inline const struct cpumask *pci_irq_get_affinity(struct pci_dev *pdev,
>  {
>  	return cpu_possible_mask;
>  }
> +
> +static inline unsigned int pci_irq_type(struct pci_dev *pdev)
> +{
> +	return PCI_IRQ_INTX;
> +}
>  #endif

[Severity: Low]
Does this also need a dummy implementation in the !CONFIG_PCI block?

This patch adds a fallback implementation for when CONFIG_PCI_MSI is disabled,
but misses adding a stub for when CONFIG_PCI is completely disabled. Other IRQ
vector API functions provide stubs in the !CONFIG_PCI block to ensure drivers
compile cleanly on architectures without PCI support:

include/linux/pci.h:
static inline int
pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
		      unsigned int max_vecs, unsigned int flags)
{
	return -ENOSPC;
}

static inline void pci_free_irq_vectors(struct pci_dev *dev)
{
}
#endif /* CONFIG_PCI */

Could the lack of a pci_irq_type() stub in include/linux/pci.h introduce a
compile regression when building a kernel with CONFIG_PCI=n where a generic
driver calls pci_irq_type()?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=4