pci_msix_free_irq() is used to free an interrupt on
a PCI/MSI-X interrupt domain.
The API description specifies that the interrupt to
be freed was allocated via pci_msix_alloc_irq_at().
This description limits the usage of pci_msix_free_irq()
since pci_msix_free_irq() can also be used to free
MSI-X interrupts allocated with, for example,
pci_alloc_irq_vectors().
Remove the text stating that the interrupt to be freed had
to be allocated with pci_msix_alloc_irq_at(). The needed
struct msi_map need not be from pci_msix_alloc_irq_at()
but can be created from scratch using pci_irq_vector()
to obtain the Linux IRQ number. Highlight that
pci_msix_free_irq() cannot be used to disable MSI-X to
guide users that, for example, pci_free_irq_vectors()
remains to be needed.
Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
Dear Maintainers,
Is my understanding correct?
For example, from my understanding the following is
correct API usage:
/*
* Enable MSI-X and allocate num interrupts.
*/
pci_alloc_irq_vectors()
/*
* Free one of the interrupts allocated via pci_alloc_irq_vectors().
* Possibly called num times, but not required.
*/
pci_msix_free_irq()
/*
* Ensure all remaining interrupts freed and MSI-X disabled.
*/
pci_free_irq_vectors()
This could be interpreted as an asymmetric usage of the API, yet
found to be practical when trying to use these new calls.
Your feedback is appreciated.
Regards,
Reinette
drivers/pci/msi/api.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/msi/api.c b/drivers/pci/msi/api.c
index b8009aa11f3c..be679aa5db64 100644
--- a/drivers/pci/msi/api.c
+++ b/drivers/pci/msi/api.c
@@ -163,11 +163,11 @@ EXPORT_SYMBOL_GPL(pci_msix_alloc_irq_at);
/**
* pci_msix_free_irq - Free an interrupt on a PCI/MSIX interrupt domain
- * which was allocated via pci_msix_alloc_irq_at()
*
* @dev: The PCI device to operate on
* @map: A struct msi_map describing the interrupt to free
- * as returned from the allocation function.
+ *
+ * Undo an interrupt vector allocation. Does not disable MSI-X.
*/
void pci_msix_free_irq(struct pci_dev *dev, struct msi_map map)
{
--
2.34.1
