kernel_optimize_test/drivers
Bjorn Helgaas 3461a06866 PCI: pciehp: Wait for hotplug command completion lazily
Previously we issued a hotplug command and waited for it to complete.  But
there's no need to wait until we're ready to issue the *next* command.  The
next command will probably be much later, so the first one may have already
completed and we may not have to actually wait at all.

Because of hardware errata, some controllers generate command completion
events for some commands but not others.  In the case of Intel CF118 (see
spec update reference), the controller indicates command completion only
for Slot Control writes that change the value of the following bits:

  Power Controller Control
  Power Indicator Control
  Attention Indicator Control
  Electromechanical Interlock Control

Changes to other bits, e.g., the interrupt enable bits, do not cause the
Command Completed bit to be set.  Controllers from AMD and Nvidia are
reported to have similar errata.

These errata cause timeouts when pcie_enable_notification() enables
interrupts.  Previously that timeout occurred at boot-time.  With this
change, the timeout occurs later, when we change the state of the slot
power, indicators, or interlock.  This speeds up boot but causes a timeout
at the first hotplug event on the slot.  Subsequent events don't timeout
because only the first (boot-time) hotplug command updates Slot Control
without touching the power/indicator/interlock controls.

Link: http://www.intel.com/content/www/us/en/processors/xeon/xeon-e7-v2-spec-update.html
Tested-by: Rajat Jain <rajatxjain@gmail.com>	(IDT 807a controller)
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
2014-06-17 15:26:02 -06:00
..
accessibility
acpi
amba
ata
atm
auxdisplay
base
bcma
block Merge git://git.infradead.org/users/willy/linux-nvme 2014-06-15 15:58:03 -10:00
bluetooth
bus
cdrom
char
clk This pull request contains the second half the of the clk changes for 2014-06-15 16:02:20 -10:00
clocksource
connector
cpufreq
cpuidle
crypto
dca
devfreq
dio
dma
edac
eisa
extcon
firewire
firmware
fmc
gpio
gpu
hid
hsi
hv
hwmon
hwspinlock
i2c
ide
idle
iio
infiniband
input
iommu
ipack
irqchip
isdn
leds
lguest
macintosh
mailbox
mcb
md
media
memory
memstick
message
mfd
misc
mmc
mtd
net vxlan: Checksum fixes 2014-06-15 01:00:50 -07:00
nfc
ntb
nubus
of
oprofile
parisc
parport
pci PCI: pciehp: Wait for hotplug command completion lazily 2014-06-17 15:26:02 -06:00
pcmcia
phy
pinctrl
platform
pnp
power
powercap
pps
ps3
ptp
pwm
rapidio
regulator
remoteproc
reset
rpmsg
rtc
s390
sbus
scsi
sfi
sh
sn
soc
spi
spmi
ssb
staging
target
tc
thermal
tty
uio
usb
uwb
vfio
vhost
video
virt
virtio
vlynq
vme
w1
watchdog
xen
zorro
Kconfig
Makefile