Re: [Patch v2 4/4] PCI, MSI: Optionally free legacy PCI IRQ when enabling MSI/MSI-X

Bjorn Helgaas
2015-06-05T21:23:02Z

>From the point of view of the generic code in this patch, freeing the IRQ
isn't optional -- there's no "if" in this this patch.

It's true that the default pcibios_free_irq() implementation does nothing,
but the changelog of this patch should describe what this patch does.

On Tue, Jun 02, 2015 at 10:49:19AM +0800, Jiang Liu wrote:
> Once PCI MSI/MSI-X is enabled by the device driver, PCI device won't
> make use of legacy PCI IRQ until PCI MSI/MSI-X is disabled again.
> So optionally free legacy PCI IRQ when enabling MSI/MSI-X and reallocate
> when disabling MSI/MSI-X.
>
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
> drivers/pci/msi.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index c3e7dfcf9ff5..47cf72c669f0 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -686,6 +686,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
> msi_set_enable(dev, 1);
> dev->msi_enabled = 1;
>
> + pcibios_free_irq(dev);
> dev->irq = entry->irq;
> return 0;
> }
> @@ -813,9 +814,10 @@ static int msix_capability_init(struct pci_dev *dev,
> /* Set MSI-X enabled bits and unmask the function */
> pci_intx_for_msi(dev, 0);
> dev->msix_enabled = 1;
> -
> msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
>
> + pcibios_free_irq(dev);
> +
> return 0;
>
> out_avail:
> @@ -930,6 +932,7 @@ void pci_msi_shutdown(struct pci_dev *dev)
>
> /* Restore dev->irq to its default pin-assertion irq */
> dev->irq = desc->msi_attrib.default_irq;
> + pcibios_alloc_irq(dev);
> }
>
> void pci_disable_msi(struct pci_dev *dev)
> @@ -1030,6 +1033,7 @@ void pci_msix_shutdown(struct pci_dev *dev)
> msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
> pci_intx_for_msi(dev, 1);
> dev->msix_enabled = 0;
> + pcibios_alloc_irq(dev);
> }
>
> void pci_disable_msix(struct pci_dev *dev)
> --
> 1.7.10.4
>