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Lukas Wunner 6c35a1ac3d PCI: pciehp: Tolerate initially unstable link 
When a device is hotplugged, Presence Detect and Link Up events often do
not occur simultaneously, but with a lag of a few milliseconds.  Only
the first event received is relevant, the other one can be disregarded.

Moreover, Stefan Roese reports that on certain platforms, Link State and
Presence Detect may flap for up to 100 ms before stabilizing, suggesting
that such events should be disregarded for at least this long:
https://lkml.kernel.org/r/20180130084121.18653-1-sr@denx.de

On slot enablement, pciehp_check_link_status() waits for 100 ms per
PCIe r4.0, sec 6.7.3.3, then probes the hotplugged device's vendor
register for up to 1 second.

If this succeeds, the link is definitely up, so ignore any Presence
Detect or Link State events that occurred up to this point.

pciehp_check_link_status() then checks the Link Training bit in the
Link Status register.  This is the final opportunity to detect
inaccessibility of the device and abort slot enablement.  Any link
or presence change that occurs afterwards will cause the slot to be
disabled again immediately after attempting to enable it.

The astute reviewer may appreciate that achieving this behavior would be
more complicated had pciehp not just been converted to enable/disable
the slot exclusively from the IRQ thread:  When the slot is enabled via
sysfs, each link or presence flap would otherwise cause the IRQ thread
to run and it would have to sense that those events are belonging to a
concurrent slot enablement operation and disregard them.  It would be
much more difficult than this mere 3 line change.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Stefan Roese <sr@denx.de>
 		2018-07-23 17:04:16 -05:00
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accessibility
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acpi pwm: Changes for v4.18-rc1 2018-06-14 16:25:43 +09:00
amba Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2018-06-06 13:49:25 -07:00
android treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
ata treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
atm treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
auxdisplay treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
base Additional power management updates for 4.18-rc1 2018-06-13 07:24:18 -07:00
bcma dma-mapping updates for 4.18: 2018-06-04 10:58:12 -07:00
block The main piece is a set of libceph changes that revamps how OSD 2018-06-15 07:24:58 +09:00
bluetooth Bluetooth: btusb: Add additional device ID for RTL8822BE 2018-05-30 15:45:01 +02:00
bus - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
cdrom treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
char docs: Fix some broken references 2018-06-15 18:10:01 -03:00
clk docs: Fix some broken references 2018-06-15 18:10:01 -03:00
clocksource treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
connector Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
cpufreq Additional power management updates for 4.18-rc1 2018-06-13 07:24:18 -07:00
cpuidle powerpc updates for 4.18 2018-06-07 10:23:33 -07:00
crypto treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
dax libnvdimm for 4.18 2018-06-08 17:21:52 -07:00
dca
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devfreq treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
dio
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dma fix a series of Documentation/ broken file name references 2018-06-15 18:10:01 -03:00
dma-buf
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edac treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
eisa
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extcon treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
firewire treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
firmware Merge branch 'akpm' (patches from Andrew) 2018-06-15 08:51:42 +09:00
fmc treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
fpga fpga: clarify that unregister functions also free 2018-05-25 18:23:56 +02:00
fsi
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gpio treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
gpu Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
hid docs: fix broken references with multiple hints 2018-06-15 18:10:01 -03:00
hsi
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hv treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
hwmon treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
hwspinlock hwspinlock updates for v4.18 2018-06-11 12:09:19 -07:00
hwtracing treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
i2c Merge branch 'i2c/for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-06-14 16:21:46 +09:00
ide treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
idle
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iio treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
infiniband treewide: Use array_size() in kvzalloc_node() 2018-06-12 16:19:22 -07:00
input docs: Fix some broken references 2018-06-15 18:10:01 -03:00
iommu - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
ipack treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
irqchip treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
isdn treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
leds treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
lightnvm docs: Fix some broken references 2018-06-15 18:10:01 -03:00
macintosh powerpc updates for 4.18 2018-06-07 10:23:33 -07:00
mailbox treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
mcb
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md docs: Fix some broken references 2018-06-15 18:10:01 -03:00
media Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
memory - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
memstick treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
message treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
mfd Merge branch 'i2c/for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-06-14 16:21:46 +09:00
misc Merge branch 'i2c/for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-06-14 16:21:46 +09:00
mmc treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
mtd - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
mux
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net Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
nfc treewide: devm_kmalloc() -> devm_kmalloc_array() 2018-06-12 16:19:22 -07:00
ntb - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
nubus Char/Misc driver patches for 4.18-rc1 2018-06-05 16:20:22 -07:00
nvdimm Merge branch 'for-4.18/mcsafe' into libnvdimm-for-next 2018-06-08 15:16:44 -07:00
nvme Merge branch 'nvme-4.18' of git://git.infradead.org/nvme into for-linus 2018-06-15 08:11:05 -06:00
nvmem treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
of - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
opp treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
oprofile treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
parisc dma-mapping updates for 4.18: 2018-06-04 10:58:12 -07:00
parport docs: Fix some broken references 2018-06-15 18:10:01 -03:00
pci PCI: pciehp: Tolerate initially unstable link 2018-07-23 17:04:16 -05:00
pcmcia treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
perf drivers/bus: arm-cci: fix build warnings 2018-05-29 16:38:16 +01:00
phy Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
pinctrl treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
platform PCI: hotplug: Demidlayer registration with the core 2018-07-23 17:04:13 -05:00
pnp media updates for v4.18-rc1 2018-06-07 12:34:37 -07:00
power treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
powercap treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
pps
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ps3
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ptp ptp_qoriq: move some definitions to header file 2018-05-28 23:05:11 -04:00
pwm pwm: Changes for v4.18-rc1 2018-06-14 16:25:43 +09:00
rapidio treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
ras
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regulator treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
remoteproc treewide: use PHYS_ADDR_MAX to avoid type casting ULLONG_MAX 2018-06-15 07:55:25 +09:00
reset - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
rpmsg rpmsg: smd: do not use mananged resources for endpoints and channels 2018-06-04 12:35:03 -07:00
rtc - New Device Support 2018-06-11 07:20:17 -07:00
s390 treewide: Use array_size() in vzalloc() 2018-06-12 16:19:22 -07:00
sbus fix a series of Documentation/ broken file name references 2018-06-15 18:10:01 -03:00
scsi SCSI fixes on 20180613 2018-06-14 16:35:32 +09:00
sfi
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sh treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
siox
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slimbus treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
sn
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soc treewide: use PHYS_ADDR_MAX to avoid type casting ULLONG_MAX 2018-06-15 07:55:25 +09:00
soundwire docs: Fix more broken references 2018-06-15 18:11:26 -03:00
spi treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
spmi
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ssb
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staging media: v4l: fix broken video4linux docs locations 2018-06-15 18:10:01 -03:00
target treewide: Use array_size() in vzalloc() 2018-06-12 16:19:22 -07:00
tc
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tee
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thermal - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
thunderbolt
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tty vfs/y2038: inode timestamps conversion to timespec64 2018-06-15 07:31:07 +09:00
uio treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
usb vfs/y2038: inode timestamps conversion to timespec64 2018-06-15 07:31:07 +09:00
uwb treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
vfio VFIO updates for v4.18 2018-06-12 13:11:26 -07:00
vhost virtio, vhost: features, fixes 2018-06-16 06:35:02 +09:00
video Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
virt treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
virtio virtio, vhost: features, fixes 2018-06-16 06:35:02 +09:00
visorbus
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vlynq
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vme
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w1 Char/Misc driver patches for 4.18-rc1 2018-06-05 16:20:22 -07:00
watchdog MIPS changes for 4.18 2018-06-12 12:56:02 -07:00
xen treewide: kvmalloc() -> kvmalloc_array() 2018-06-12 16:19:22 -07:00
zorro - Introduce arithmetic overflow test helper functions (Rasmus) 2018-06-06 17:27:14 -07:00
Kconfig
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Makefile
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