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authorBjorn Helgaas <bhelgaas@google.com>2017-02-15 20:56:10 +0300
committerBjorn Helgaas <bhelgaas@google.com>2017-02-15 20:56:10 +0300
commit3ec2574e31b5aebeeed52ea784bb6d7960788202 (patch)
treed24b479916711f1b8e112f5775839bbe9ff41be1 /Documentation/PCI
parent906c142634def5dd3dda533d5d20bd3c1c19d1fb (diff)
parente4e7d59704d485f272061cea9057798dda3cfd99 (diff)
downloadlinux-3ec2574e31b5aebeeed52ea784bb6d7960788202.tar.xz
Merge branch 'pci/msi' into next
* pci/msi: PCI/MSI: Update MSI/MSI-X bits in PCIEBUS-HOWTO PCI/MSI: Document pci_alloc_irq_vectors(), deprecate pci_enable_msi() PCI/MSI: Return -ENOSPC if pci_enable_msi_range() can't get enough vectors PCI/portdrv: Use pci_irq_alloc_vectors() PCI/MSI: Check that we have a legacy interrupt line before using it PCI/MSI: Remove pci_msi_domain_{alloc,free}_irqs() PCI/MSI: Remove unused pci_msi_create_default_irq_domain() PCI/MSI: Return failure when msix_setup_entries() fails PCI/MSI: Remove pci_enable_msi_{exact,range}() amd-xgbe: Update PCI support to use new IRQ functions [media] cobalt: use pci_irq_allocate_vectors() PCI/MSI: Fix msi_capability_init() kernel-doc warnings
Diffstat (limited to 'Documentation/PCI')
-rw-r--r--Documentation/PCI/MSI-HOWTO.txt6
-rw-r--r--Documentation/PCI/PCIEBUS-HOWTO.txt33
-rw-r--r--Documentation/PCI/pci.txt24
3 files changed, 21 insertions, 42 deletions
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index cd9c9f6a7cd9..1e37138027a3 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -162,8 +162,6 @@ The following old APIs to enable and disable MSI or MSI-X interrupts should
not be used in new code:
pci_enable_msi() /* deprecated */
- pci_enable_msi_range() /* deprecated */
- pci_enable_msi_exact() /* deprecated */
pci_disable_msi() /* deprecated */
pci_enable_msix_range() /* deprecated */
pci_enable_msix_exact() /* deprecated */
@@ -268,5 +266,5 @@ or disabled (0). If 0 is found in any of the msi_bus files belonging
to bridges between the PCI root and the device, MSIs are disabled.
It is also worth checking the device driver to see whether it supports MSIs.
-For example, it may contain calls to pci_enable_msi_range() or
-pci_enable_msix_range().
+For example, it may contain calls to pci_irq_alloc_vectors() with the
+PCI_IRQ_MSI or PCI_IRQ_MSIX flags.
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
diff --git a/Documentation/PCI/pci.txt b/Documentation/PCI/pci.txt
index 77f49dc5be23..611a75e4366e 100644
--- a/Documentation/PCI/pci.txt
+++ b/Documentation/PCI/pci.txt
@@ -382,18 +382,18 @@ The fundamental difference between MSI and MSI-X is how multiple
"vectors" get allocated. MSI requires contiguous blocks of vectors
while MSI-X can allocate several individual ones.
-MSI capability can be enabled by calling pci_enable_msi() or
-pci_enable_msix() before calling request_irq(). This causes
-the PCI support to program CPU vector data into the PCI device
-capability registers.
-
-If your PCI device supports both, try to enable MSI-X first.
-Only one can be enabled at a time. Many architectures, chip-sets,
-or BIOSes do NOT support MSI or MSI-X and the call to pci_enable_msi/msix
-will fail. This is important to note since many drivers have
-two (or more) interrupt handlers: one for MSI/MSI-X and another for IRQs.
-They choose which handler to register with request_irq() based on the
-return value from pci_enable_msi/msix().
+MSI capability can be enabled by calling pci_alloc_irq_vectors() with the
+PCI_IRQ_MSI and/or PCI_IRQ_MSIX flags before calling request_irq(). This
+causes the PCI support to program CPU vector data into the PCI device
+capability registers. Many architectures, chip-sets, or BIOSes do NOT
+support MSI or MSI-X and a call to pci_alloc_irq_vectors with just
+the PCI_IRQ_MSI and PCI_IRQ_MSIX flags will fail, so try to always
+specify PCI_IRQ_LEGACY as well.
+
+Drivers that have different interrupt handlers for MSI/MSI-X and
+legacy INTx should chose the right one based on the msi_enabled
+and msix_enabled flags in the pci_dev structure after calling
+pci_alloc_irq_vectors.
There are (at least) two really good reasons for using MSI:
1) MSI is an exclusive interrupt vector by definition.