PCI: Create revision file in sysfs

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Currently the revision isn't available via sysfs/libudev thus if one wants
to know the value one needs to read through the config file, which can be
quite time-consuming because it wakes/powers up the device.

There are at least two userspace components which could make use the new
file: libpciaccess and libdrm.  The former wakes up _every_ PCI device,
which can be observed via glxinfo when using Mesa 10.0+ drivers.  The
latter, in association with Mesa 13.0, can lead to 2-3 second delays while
starting firefox, thunderbird or chromium.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=98502
Tested-by: Mauro Santos <registo.mailling@gmail.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch
CC: Greg KH <gregkh@linuxfoundation.org>

...

This commit is contained in:

Emil Velikov 2016-11-21 16:24:49 -06:00 • committed by Bjorn Helgaas

parent 1001354ca3

commit 702ed3be1b

3 changed files with 11 additions and 0 deletions

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7

Documentation/ABI/testing/sysfs-bus-pci

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2

Documentation/filesystems/sysfs-pci.txt

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2

drivers/pci/pci-sysfs.c

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