Re: [PATCH 13/13] PCI: Deprecate pci_intx(), pcim_intx()

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 15 Oct 2024 20:51:23 +0200
Philipp Stanner <pstanner@redhat.com> wrote:

> pci_intx() and its managed counterpart pcim_intx() only exist for older
> drivers which have not been ported yet for various reasons. Future
> drivers should preferably use pci_alloc_irq_vectors().
> 
> Mark pci_intx() and pcim_intx() as deprecated and encourage usage of
> pci_alloc_irq_vectors() in its place.

I don't really understand this.  As we've discussed previously
pci_alloc_irq_vectors() is, unsurprisingly, for allocating PCI IRQ
vectors while pci_intx() is for manipulating the INTx disable bit on
PCI devices.  The latter is a generic mechanism for preventing PCI
devices from generating INTx, regardless of whether there's a vector
allocated for it.  How does the former replace the latter and why do we
feel the need to deprecate the latter?

It feels like this fits some narrow narrative and makes all users of
these now deprecated functions second class citizens.  Why?  At it's
root these are simply providing mask and set or mask and clear register
bit operations.  Thanks,

Alex
 
> Signed-off-by: Philipp Stanner <pstanner@redhat.com>
> ---
>  drivers/pci/devres.c | 5 ++++-
>  drivers/pci/pci.c    | 5 ++++-
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
> index 6f8f712fe34e..4c76fc063104 100644
> --- a/drivers/pci/devres.c
> +++ b/drivers/pci/devres.c
> @@ -435,7 +435,7 @@ static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
>  }
>  
>  /**
> - * pcim_intx - managed pci_intx()
> + * pcim_intx - managed pci_intx() (DEPRECATED)
>   * @pdev: the PCI device to operate on
>   * @enable: boolean: whether to enable or disable PCI INTx
>   *
> @@ -443,6 +443,9 @@ static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
>   *
>   * Enable/disable PCI INTx for device @pdev.
>   * Restore the original state on driver detach.
> + *
> + * This function is DEPRECATED. Do not use it in new code.
> + * Use pci_alloc_irq_vectors() instead (there is no managed version, currently).
>   */
>  int pcim_intx(struct pci_dev *pdev, int enable)
>  {
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7ce1d0e3a1d5..dc69e23b8982 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4477,11 +4477,14 @@ void pci_disable_parity(struct pci_dev *dev)
>  }
>  
>  /**
> - * pci_intx - enables/disables PCI INTx for device dev
> + * pci_intx - enables/disables PCI INTx for device dev (DEPRECATED)
>   * @pdev: the PCI device to operate on
>   * @enable: boolean: whether to enable or disable PCI INTx
>   *
>   * Enables/disables PCI INTx for device @pdev
> + *
> + * This function is DEPRECATED. Do not use it in new code.
> + * Use pci_alloc_irq_vectors() instead.
>   */
>  void pci_intx(struct pci_dev *pdev, int enable)
>  {