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authorChristoph Hellwig <hch@lst.de>2017-02-15 08:58:23 +0100
committerBjorn Helgaas <bhelgaas@google.com>2017-02-15 11:51:33 -0600
commite4e7d59704d485f272061cea9057798dda3cfd99 (patch)
tree08a36f4ec4760231aadc5ecf4d0d6b3068cde139 /Documentation/PCI
parentc3cf2c61ddc1410424da0ea87717edf16fc296c5 (diff)
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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')
-rw-r--r--Documentation/PCI/PCIEBUS-HOWTO.txt33
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