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PCI: Use positive flags in pci_alloc_irq_vectors()

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Instead of passing negative flags like PCI_IRQ_NOMSI to prevent use of
certain interrupt types, pass positive flags like PCI_IRQ_LEGACY,
PCI_IRQ_MSI, etc., to specify the acceptable interrupt types.

This is based on a number of pending driver conversions that just happend
to be a whole more obvious to read this way, and given that we have no
users in the tree yet it can still easily be done.

I've also added a PCI_IRQ_ALL_TYPES catchall to keep the case of accepting
all interrupt types very simple.

[bhelgaas: changelog, fix PCI_IRQ_AFFINITY doc typo, remove mention of
PCI_IRQ_NOLEGACY]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexander Gordeev <agordeev@redhat.com>
This commit is contained in:
Christoph Hellwig 2016-08-11 07:11:04 -07:00 • committed by Bjorn Helgaas
parent 8b078c6032
commit 4fe0d15488
3 changed files with 23 additions and 26 deletions
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24
Documentation/PCI/MSI-HOWTO.txt
View file

@ -94,14 +94,11 @@ has a requirements for a minimum number of vectors the driver can pass a
min_vecs argument set to this limit, and the PCI core will return -ENOSPC
if it can't meet the minimum number of vectors.
The flags argument should normally be set to 0, but can be used to pass the
PCI_IRQ_NOMSI and PCI_IRQ_NOMSIX flag in case a device claims to support
MSI or MSI-X, but the support is broken, or to pass PCI_IRQ_NOLEGACY in
case the device does not support legacy interrupt lines.
By default this function will spread the interrupts around the available
CPUs, but this feature can be disabled by passing the PCI_IRQ_NOAFFINITY
flag.
The flags argument is used to specify which type of interrupt can be used
by the device and the driver (PCI_IRQ_LEGACY, PCI_IRQ_MSI, PCI_IRQ_MSIX).
A convenient short-hand (PCI_IRQ_ALL_TYPES) is also available to ask for
any possible kind of interrupt. If the PCI_IRQ_AFFINITY flag is set,
pci_alloc_irq_vectors() will spread the interrupts around the available CPUs.
To get the Linux IRQ numbers passed to request_irq() and free_irq() and the
vectors, use the following function:
@ -131,7 +128,7 @@ larger than the number supported by the device it will automatically be
capped to the supported limit, so there is no need to query the number of
vectors supported beforehand:
nvec = pci_alloc_irq_vectors(pdev, 1, nvec, 0);
nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_ALL_TYPES)
if (nvec < 0)
goto out_err;
@ -140,7 +137,7 @@ interrupts it can request a particular number of interrupts by passing that
number to pci_alloc_irq_vectors() function as both 'min_vecs' and
'max_vecs' parameters:
ret = pci_alloc_irq_vectors(pdev, nvec, nvec, 0);
ret = pci_alloc_irq_vectors(pdev, nvec, nvec, PCI_IRQ_ALL_TYPES);
if (ret < 0)
goto out_err;
@ -148,15 +145,14 @@ The most notorious example of the request type described above is enabling
the single MSI mode for a device. It could be done by passing two 1s as
'min_vecs' and 'max_vecs':
ret = pci_alloc_irq_vectors(pdev, 1, 1, 0);
ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
if (ret < 0)
goto out_err;
Some devices might not support using legacy line interrupts, in which case
the PCI_IRQ_NOLEGACY flag can be used to fail the request if the platform
can't provide MSI or MSI-X interrupts:
the driver can specify that only MSI or MSI-X is acceptable:
nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_NOLEGACY);
nvec = pci_alloc_irq_vectors(pdev, 1, nvec, PCI_IRQ_MSI | PCI_IRQ_MSIX);
if (nvec < 0)
goto out_err;