Re: [PATCH] Documentation: PCI: Clarify pci_free_irq_vectors() usage for managed devices

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Philipp, any comment? would like your ack if possible]

On Mon, Jan 26, 2026 at 10:57:13AM +0800, Shawn Lin wrote:
> Update the msi-howto.rst documentation to clarify that drivers using the
> resource-managed function pcim_enable_device() must not call pci_free_irq_vectors().
> This is because such devices have automatic IRQ vector management via pcim_msi_release(),
> which is registered by pci_setup_msi_context() when pdev->is_managed is true.
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> ---
> 
>  Documentation/PCI/msi-howto.rst | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/PCI/msi-howto.rst b/Documentation/PCI/msi-howto.rst
> index 667ebe2..dc85f1e 100644
> --- a/Documentation/PCI/msi-howto.rst
> +++ b/Documentation/PCI/msi-howto.rst
> @@ -113,8 +113,11 @@ vectors, use the following function::
>  
>    int pci_irq_vector(struct pci_dev *dev, unsigned int nr);
>  
> -Any allocated resources should be freed before removing the device using
> -the following function::
> +If the driver enables the device using the resource-managed function
> +pcim_enable_device(), the driver shouldn't call pci_free_irq_vectors()
> +because the IRQ vectors are automatically managed. Otherwise, the driver
> +should free any allocated IRQ vectors before removing the device using the
> +following function::
>  
>    void pci_free_irq_vectors(struct pci_dev *dev);
>  
> -- 
> 2.7.4
>