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PCI: Document /sys/bus/pci/devices/.../irq

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Document /sys/bus/pci/devices/.../irq.

This file contains the IRQ of the INTx interrupt (or zero if the device
doesn't support INTx interrupts).

If the device has enabled MSI (not MSI-X), it contains the first MSI IRQ
instead.  This is a historical mistake because devices may support several
MSI or MSI-X vectors, and this file can't contain them all.  But we
preserve this behavior to avoid breaking userspace.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20210825102636.52757-2-21cnbao@gmail.com
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Barry Song 2021-08-25 18:26:34 +08:00 committed by Bjorn Helgaas
parent e4e737bb5c
commit 5e3be666f4
1 changed files with 11 additions and 0 deletions
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Documentation/ABI/testing/sysfs-bus-pci
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@ -96,6 +96,17 @@ Description:
This attribute indicates the mode that the irq vector named by
the file is in (msi vs. msix)
What: /sys/bus/pci/devices/.../irq
Date: August 2021
Contact: Linux PCI developers <linux-pci@vger.kernel.org>
Description:
If a driver has enabled MSI (not MSI-X), "irq" contains the
IRQ of the first MSI vector. Otherwise "irq" contains the
IRQ of the legacy INTx interrupt.
"irq" being set to 0 indicates that the device isn't
capable of generating legacy INTx interrupts.
What: /sys/bus/pci/devices/.../remove
Date: January 2009
Contact: Linux PCI developers <linux-pci@vger.kernel.org>