diff options
Diffstat (limited to 'Documentation/PCI')
| -rw-r--r-- | Documentation/PCI/MSI-HOWTO.txt | 39 |
1 files changed, 6 insertions, 33 deletions
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index a8b41788dfde..aa4ad987510d 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -127,49 +127,22 @@ on the number of vectors that can be allocated; pci_enable_msi_block() returns as soon as it finds any constraint that doesn't allow the call to succeed. -4.2.3 pci_enable_msi_block_auto - -int pci_enable_msi_block_auto(struct pci_dev *dev, int *count) - -This variation on pci_enable_msi() call allows a device driver to request -the maximum possible number of MSIs. The MSI specification only allows -interrupts to be allocated in powers of two, up to a maximum of 2^5 (32). - -If this function returns a positive number, it indicates that it has -succeeded and the returned value is the number of allocated interrupts. In -this case, the function enables MSI on this device and updates dev->irq to -be the lowest of the new interrupts assigned to it. The other interrupts -assigned to the device are in the range dev->irq to dev->irq + returned -value - 1. - -If this function returns a negative number, it indicates an error and -the driver should not attempt to request any more MSI interrupts for -this device. - -If the device driver needs to know the number of interrupts the device -supports it can pass the pointer count where that number is stored. The -device driver must decide what action to take if pci_enable_msi_block_auto() -succeeds, but returns a value less than the number of interrupts supported. -If the device driver does not need to know the number of interrupts -supported, it can set the pointer count to NULL. - -4.2.4 pci_disable_msi +4.2.3 pci_disable_msi void pci_disable_msi(struct pci_dev *dev) This function should be used to undo the effect of pci_enable_msi() or -pci_enable_msi_block() or pci_enable_msi_block_auto(). Calling it restores -dev->irq to the pin-based interrupt number and frees the previously -allocated message signaled interrupt(s). The interrupt may subsequently be -assigned to another device, so drivers should not cache the value of -dev->irq. +pci_enable_msi_block(). Calling it restores dev->irq to the pin-based +interrupt number and frees the previously allocated message signaled +interrupt(s). The interrupt may subsequently be assigned to another +device, so drivers should not cache the value of dev->irq. Before calling this function, a device driver must always call free_irq() on any interrupt for which it previously called request_irq(). Failure to do so results in a BUG_ON(), leaving the device with MSI enabled and thus leaking its vector. -4.2.5 pci_msi_vec_count +4.2.4 pci_msi_vec_count int pci_msi_vec_count(struct pci_dev *dev) |