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PCI/MSI: Add "msi_bus" sysfs MSI/MSI-X control for endpoints

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The "msi_bus" sysfs file for bridges sets a bus flag to allow or disallow
future driver requests for MSI or MSI-X.  Previously, the sysfs file
existed for endpoints but did nothing.

Add "msi_bus" support for endpoints, so an administrator can prevent the
use of MSI and MSI-X for individual devices.

Note that as for bridges, these changes only affect future driver requests
for MSI or MSI-X, so drivers may need to be reloaded.

Add documentation for the "msi_bus" sysfs file.

[bhelgaas: changelog, comments, add "subordinate", add endpoint printk,
rework bus_flags setting, make bus_flags printk unconditional]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Yijing Wang
2014-09-23 13:27:24 +08:00
committed by Bjorn Helgaas
parent 48c3c38f00
commit 468ff15a3a
2 changed files with 29 additions and 20 deletions
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10
Documentation/ABI/testing/sysfs-bus-pci
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@@ -65,6 +65,16 @@ Description:
force a rescan of all PCI buses in the system, and
re-discover previously removed devices.
What: /sys/bus/pci/devices/.../msi_bus
Date: September 2014
Contact: Linux PCI developers <linux-pci@vger.kernel.org>
Description:
Writing a zero value to this attribute disallows MSI and
MSI-X for any future drivers of the device. If the device
is a bridge, MSI and MSI-X will be disallowed for future
drivers of all child devices under the bridge. Drivers
must be reloaded for the new setting to take effect.
What: /sys/bus/pci/devices/.../msi_irqs/
Date: September, 2011
Contact: Neil Horman <nhorman@tuxdriver.com>