Change the chapters related to uio_pci_generic that refer interrupt mode.
Add the relevant explanation regarding MSI and MSI-X interrupt modes
support.
Signed-off-by: Vlad Zolotarov <vl...@cloudius-systems.com>
---
Documentation/DocBook/uio-howto.tmpl | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
diff --git a/Documentation/DocBook/uio-howto.tmpl
b/Documentation/DocBook/uio-howto.tmpl
index cd0e452..a176129 100644
--- a/Documentation/DocBook/uio-howto.tmpl
+++ b/Documentation/DocBook/uio-howto.tmpl
@@ -46,6 +46,12 @@ GPL version 2.
<revhistory>
<revision>
+ <revnumber>0.10</revnumber>
+ <date>2015-10-04</date>
+ <authorinitials>vz</authorinitials>
+ <revremark>Added MSI and MSI-X support to uio_pci_generic.</revremark>
+ </revision>
+ <revision>
<revnumber>0.9</revnumber>
<date>2009-07-16</date>
<authorinitials>mst</authorinitials>
@@ -935,15 +941,32 @@ and look in the output for failure reasons
<sect1 id="uio_pci_generic_internals">
<title>Things to know about uio_pci_generic</title>
<para>
-Interrupts are handled using the Interrupt Disable bit in the PCI command
+Interrupts are handled either as MSI-X or MSI interrupts (if the device
supports it) or
+as legacy INTx interrupts. By default INTx interrupts are used.
+ </para>
+ <para>
+uio_pci_generic automatically configures a device to use INTx interrupt for
backward
+compatibility. If INTx are not available MSI-X interrupts will be used if the
device
+supports it and if not MSI interrupts are going to be used. If none of the
interrupts
+modes is supported probe() will fail.
+ </para>
+ <para>
+To get the used interrupt mode application has to use
UIO_PCI_GENERIC_INT_MODE_GET ioctl
+command.
+UIO_PCI_GENERIC_IRQ_NUM_GET ioctl command may be used to get the total number
of IRQs.
+Then UIO_PCI_GENERIC_IRQ_SET ioctl command may be used to bind a specific
eventfd to a specific
+IRQ vector.
+ </para>
+ <para>
+Legacy interrupts are handled using the Interrupt Disable bit in the PCI
command
register and Interrupt Status bit in the PCI status register. All devices
compliant to PCI 2.3 (circa 2002) and all compliant PCI Express devices should
support these bits. uio_pci_generic detects this support, and won't bind to
devices which do not support the Interrupt Disable Bit in the command register.
</para>
<para>
-On each interrupt, uio_pci_generic sets the Interrupt Disable bit.
-This prevents the device from generating further interrupts
+If legacy interrupts are used, uio_pci_generic sets the Interrupt Disable bit
on
+each interrupt. This prevents the device from generating further interrupts
until the bit is cleared. The userspace driver should clear this
bit before blocking and waiting for more interrupts.
</para>
--
2.1.0
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