diff options
| author | Christoph Hellwig <hch@lst.de> | 2017-02-15 10:58:23 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2017-02-15 20:51:33 +0300 |
| commit | e4e7d59704d485f272061cea9057798dda3cfd99 (patch) | |
| tree | 08a36f4ec4760231aadc5ecf4d0d6b3068cde139 /Documentation/PCI/PCIEBUS-HOWTO.txt | |
| parent | c3cf2c61ddc1410424da0ea87717edf16fc296c5 (diff) | |
| download | linux-e4e7d59704d485f272061cea9057798dda3cfd99.tar.xz | |
PCI/MSI: Update MSI/MSI-X bits in PCIEBUS-HOWTO
Update the MSI/MSI-X bits in PCIEBUS-HOWTO. Stop talking about low-level
details that mention deprecated APIs and concentrate on what service
drivers should do and why.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'Documentation/PCI/PCIEBUS-HOWTO.txt')
| -rw-r--r-- | Documentation/PCI/PCIEBUS-HOWTO.txt | 33 |
1 files changed, 7 insertions, 26 deletions
diff --git a/Documentation/PCI/PCIEBUS-HOWTO.txt b/Documentation/PCI/PCIEBUS-HOWTO.txt index 6bd5f372adec..15f0bb3b5045 100644 --- a/Documentation/PCI/PCIEBUS-HOWTO.txt +++ b/Documentation/PCI/PCIEBUS-HOWTO.txt @@ -161,21 +161,13 @@ Since all service drivers of a PCI-PCI Bridge Port device are allowed to run simultaneously, below lists a few of possible resource conflicts with proposed solutions. -6.1 MSI Vector Resource - -The MSI capability structure enables a device software driver to call -pci_enable_msi to request MSI based interrupts. Once MSI interrupts -are enabled on a device, it stays in this mode until a device driver -calls pci_disable_msi to disable MSI interrupts and revert back to -INTx emulation mode. Since service drivers of the same PCI-PCI Bridge -port share the same physical device, if an individual service driver -calls pci_enable_msi/pci_disable_msi it may result unpredictable -behavior. For example, two service drivers run simultaneously on the -same physical Root Port. Both service drivers call pci_enable_msi to -request MSI based interrupts. A service driver may not know whether -any other service drivers have run on this Root Port. If either one -of them calls pci_disable_msi, it puts the other service driver -in a wrong interrupt mode. +6.1 MSI and MSI-X Vector Resource + +Once MSI or MSI-X interrupts are enabled on a device, it stays in this +mode until they are disabled again. Since service drivers of the same +PCI-PCI Bridge port share the same physical device, if an individual +service driver enables or disables MSI/MSI-X mode it may result +unpredictable behavior. To avoid this situation all service drivers are not permitted to switch interrupt mode on its device. The PCI Express Port Bus driver @@ -187,17 +179,6 @@ driver. Service drivers should use (struct pcie_device*)dev->irq to call request_irq/free_irq. In addition, the interrupt mode is stored in the field interrupt_mode of struct pcie_device. -6.2 MSI-X Vector Resources - -Similar to the MSI a device driver for an MSI-X capable device can -call pci_enable_msix to request MSI-X interrupts. All service drivers -are not permitted to switch interrupt mode on its device. The PCI -Express Port Bus driver is responsible for determining the interrupt -mode and this should be transparent to service drivers. Any attempt -by service driver to call pci_enable_msix/pci_disable_msix may -result unpredictable behavior. Service drivers should use -(struct pcie_device*)dev->irq and call request_irq/free_irq. - 6.3 PCI Memory/IO Mapped Regions Service drivers for PCI Express Power Management (PME), Advanced |