Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-16 09:02:00 +00:00
Code Issues Packages Projects Releases Wiki Activity
fe724bf9f0
linux/drivers
History
Daniel Kurtz fe724bf9f0 i2c: s3c2410: use exponential back off while polling for bus idle 
Usually, the i2c controller has finished emitting the i2c STOP before the
driver reaches the bus idle polling loop.  Optimize for this most common
case by reading IICSTAT first and potentially skipping the loop.

If the cpu is faster than the hardware, we wait for bus idle in a polling
loop.  However, since the duration of one iteration of the loop is
dependent on cpu freq, and this i2c IP is used on many different systems,
use a time based loop timeout (5 ms).

We would like very low latencies to detect bus idle for the normal
'fast' case.  However, if a device is slow to release the bus for some
reason, it could hold off the STOP generation for up to several
milliseconds.  Rapidly polling for bus idle would seriously load the CPU
while waiting for it to release the bus.  So, use a partial exponential
backoff as a compromise between idle detection latency and cpu load.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
2012-11-16 13:09:33 +01:00
..
accessibility
acpi ACPI video: Ignore errors after _DOD evaluation. 2012-11-03 09:52:54 +08:00
amba
ata Merge branch 'samsung_platform_data' into staging/for_v3.7 2012-10-05 22:32:05 -03:00
atm sections: fix section conflicts in drivers/atm 2012-10-06 03:04:40 +09:00
auxdisplay
base Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2012-11-10 21:58:34 +01:00
bcma bcma: fix unregistration of cores 2012-10-15 14:45:51 -04:00
block loop: Make explicit loop device destruction lazy 2012-10-30 08:37:31 +01:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-10-02 13:38:27 -07:00
bus drivers: bus: omap_l3: fixup merge conflict resolution 2012-10-01 19:39:48 -07:00
cdrom
char sonypi: suspend/resume callbacks should be conditionally compiled on CONFIG_PM_SLEEP 2012-10-25 12:05:50 -07:00
clk spi: Updates for v3.7 2012-10-02 17:26:42 -07:00
clocksource Power management updates for 3.7-rc1 2012-10-02 18:32:35 -07:00
connector Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2012-10-02 13:38:27 -07:00
cpufreq cpufreq / powernow-k8: Change maintainer's email address 2012-10-31 21:02:57 +01:00
cpuidle ACPI idle, CPU hotplug: Fix NULL pointer dereference during hotplug 2012-10-08 22:52:54 -04:00
crypto ARM: soc: late platform updates 2012-10-07 20:55:16 +09:00
dca
devfreq
dio
dma Merge branch 'fixes' of git://git.infradead.org/users/vkoul/slave-dma 2012-10-26 14:59:01 -07:00
edac amd64_edac:__amd64_set_scrub_rate(): avoid overindexing scrubrates[] 2012-10-24 16:13:27 +02:00
eisa
extcon extcon : register for cable interest by cable name 2012-10-23 16:32:18 +09:00
firewire firewire: cdev: fix user memory corruption (i386 userland on amd64 kernel) 2012-10-09 18:26:28 +02:00
firmware firmware/memmap: avoid type conflicts with the generic memmap_init() 2012-10-19 14:07:47 -07:00
gpio Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2012-11-10 21:58:34 +01:00
gpu drm/vmwgfx: Fix a case where the code would BUG when trying to pin GMR memory 2012-11-09 20:49:06 +10:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2012-11-09 06:56:23 +01:00
hsi
hv Drivers: hv: Cleanup error handling in vmbus_open() 2012-10-24 15:46:27 -07:00
hwmon hwmon: Fix chip feature table headers 2012-11-05 21:54:40 +01:00
hwspinlock
i2c i2c: s3c2410: use exponential back off while polling for bus idle 2012-11-16 13:09:33 +01:00
ide sections: fix section conflicts in drivers/ide 2012-10-06 03:04:41 +09:00
idle
iio iio: Remove duplicates for light/ in Kconfig and Makefile 2012-10-19 19:44:06 +01:00
infiniband Merge branches 'cxgb4' and 'mlx4' into for-next 2012-10-23 09:03:49 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2012-11-02 16:11:15 -07:00
iommu iommu/tegra: smmu: Fix deadly typo 2012-10-24 16:58:53 +02:00
irqchip
isdn isdn: Make CONFIG_ISDN depend on CONFIG_NETDEVICES 2012-11-07 18:59:26 -05:00
leds Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds 2012-10-10 20:14:07 +09:00
lguest Merge branch 'virtio-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-07 21:04:56 +09:00
macintosh Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2012-10-06 03:16:12 +09:00
md MD RAID10: Fix oops when creating RAID10 arrays via dm-raid.c 2012-10-31 11:42:30 +11:00
media [media] Kconfig: Fix dependencies for driver autoselect options 2012-10-17 16:45:56 -03:00
memory
memstick
message
mfd 1. New drivers: 2012-10-07 17:29:24 +09:00
misc pwm: Changes for v3.7-rc1 2012-10-10 20:15:24 +09:00
mmc mmc: sdhci-s3c: fix the card detection in runtime-pm 2012-11-07 15:40:52 -05:00
mtd mtd: Disable mtdchar mmap on MMU systems 2012-10-09 15:08:42 +01:00
net gianfar: ethernet vanishes after restoring from hibernation 2012-11-09 17:08:36 -05:00
nfc
nubus
of of/platform: sparse fix 2012-10-17 15:53:03 -05:00
oprofile mm: use mm->exe_file instead of first VM_EXECUTABLE vma->vm_file 2012-10-09 16:22:18 +09:00
parisc
parport Xtensa patchset for 3.7 2012-10-09 16:11:46 +09:00
pci PCI/portdrv: Don't create hotplug slots unless port supports hotplug 2012-11-05 16:59:59 -07:00
pcmcia Merge branch 'testing/driver-warnings' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc into fixes 2012-10-19 15:40:18 -07:00
pinctrl pinctrl: samsung and exynos need to depend on OF && GPIOLIB 2012-11-06 10:02:14 +01:00
platform Merge branches 'fixes-for-37', 'ec' and 'thermal' into release 2012-10-09 01:47:35 -04:00
pnp
power Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2012-10-13 11:27:59 +09:00
pps idr: rename MAX_LEVEL to MAX_IDR_LEVEL 2012-10-06 03:04:56 +09:00
ps3
ptp
pwm pwm: Changes for v3.7-rc1 2012-10-10 20:15:24 +09:00
rapidio rapidio: update for destination ID allocation 2012-10-11 08:50:15 +09:00
regulator MFD bits for the 3.7 merge window. 2012-10-05 12:01:30 +09:00
remoteproc Merge branch 'virtio-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-07 21:04:56 +09:00
rpmsg Merge branch 'virtio-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-07 21:04:56 +09:00
rtc drivers/rtc/rtc-imxdi.c: add missing spin lock initialization 2012-10-25 14:37:53 -07:00
s390 s390/cio: fix length calculation in idset.c 2012-11-06 22:39:54 +01:00
sbus
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2012-11-10 21:58:34 +01:00
sfi
sh sh: Fix up more fallout from pointless ARM __iomem churn. 2012-10-15 14:08:48 +09:00
sn
spi spi: Some minor MXS fixes 2012-10-28 11:13:54 -07:00
ssb
staging Staging driver fixes for 3.7-rc3 2012-10-26 10:25:31 -07:00
target target: Fix incorrect usage of nested IRQ spinlocks in ABORT_TASK path 2012-11-01 00:38:45 -07:00
tc
thermal exynos4_tmu_driver_ids should be exynos_tmu_driver_ids. 2012-11-03 09:52:55 +08:00
tty Revert "serial: omap: fix software flow control" 2012-10-24 11:57:21 -07:00
uio mm: kill vma flag VM_RESERVED and mm->reserved_vm counter 2012-10-09 16:22:19 +09:00
usb usb: gadget: g_ether: fix frame size check for 802.1Q 2012-11-07 21:12:26 -05:00
uwb
vfio vfio: Fix PCI INTx disable consistency 2012-10-10 09:10:32 -06:00
vhost vhost: fix mergeable bufs on BE hosts 2012-10-24 23:19:30 -04:00
video Bug-fixes: 2012-11-02 13:26:11 -07:00
virt
virtio virtio: Don't access index after unregister. 2012-11-09 14:54:24 +10:30
vlynq
vme
w1 char/misc driver merge for 3.7-rc1 2012-10-01 12:09:59 -07:00
watchdog Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2012-10-07 21:06:10 +09:00
xen Bug-fixes: 2012-11-10 06:56:21 +01:00
zorro
Kconfig ARM: soc: driver specific changes 2012-10-01 18:46:13 -07:00
Makefile IPMI: Change link order 2012-10-16 18:07:12 -07:00