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linux-2.6/Documentation
Sujit Reddy Thumma 597dd9d79c mmc: core: Use delayed work in clock gating framework
Current clock gating framework disables the MCI clock as soon as the
request is completed and enables it when a request arrives. This aggressive
clock gating framework, when enabled, cause following issues:

When there are back-to-back requests from the Queue layer, we unnecessarily
end up disabling and enabling the clocks between these requests since 8MCLK
clock cycles is a very short duration compared to the time delay between
back to back requests reaching the MMC layer. This overhead can effect the
overall performance depending on how long the clock enable and disable
calls take which is platform dependent. For example on some platforms we
can have clock control not on the local processor, but on a different
subsystem and the time taken to perform the clock enable/disable can add
significant overhead.

Also if the host controller driver decides to disable the host clock too
when mmc_set_ios function is called with ios.clock=0, it adds additional
delay and it is highly possible that the next request had already arrived
and unnecessarily blocked in enabling the clocks. This is seen frequently
when the processor is executing at high speeds and in multi-core platforms
thus reduces the overall throughput compared to if clock gating is
disabled.

Fix this by delaying turning off the clocks by posting request on
delayed workqueue. Also cancel the unscheduled pending work, if any,
when there is access to card.

sysfs entry is provided to tune the delay as needed, default
value set to 200ms.

Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
2012-01-11 23:58:41 -05:00
..
ABI Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2011-12-13 14:59:42 -08:00
accounting Documentation: update cgroupfs mount point 2011-06-15 21:52:50 -07:00
acpi ACPI, APEI, EINJ Param support is disabled by default 2011-08-03 11:15:59 -04:00
aoe
arm Merge branch 'next/deletion' of git+ssh://master.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc 2011-07-25 12:43:28 -07:00
auxdisplay
blackfin doc: fix broken references 2011-09-27 18:08:04 +02:00
block Documentation: drop as block elevator reference in switching-sched.txt 2011-11-04 12:01:48 -07:00
blockdev cciss: auto engage SCSI mid layer at driver load time 2011-11-16 09:21:49 +01:00
cdrom doc: fix broken references 2011-09-27 18:08:04 +02:00
cgroups Documentation: Fix typo in freezer-subsystem.txt 2011-11-07 23:02:25 +01:00
connector
console
cpu-freq Fix documentation and comment typo 'no_hz' 2011-08-08 18:55:59 +02:00
cpuidle
cris
crypto
development-process doc: fix broken references 2011-09-27 18:08:04 +02:00
device-mapper dm log userspace: fix comment hyphens 2011-10-31 20:21:22 +00:00
devicetree of: Add Silicon Image vendor prefix 2011-11-29 08:24:20 -06:00
DocBook Merge branch 'driver-core-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core 2011-11-21 20:36:26 -08:00
driver-model docs/driver-model: Update device class docs 2011-08-24 16:01:24 -07:00
dvb [media] update az6027 firmware URL 2011-10-14 10:29:45 -03:00
early-userspace
fault-injection fault-injection: update documentation with the mmc module param 2011-10-26 16:32:13 -04:00
fb udlfb: Enable fbcon access to framebuffer by default 2011-08-24 10:12:38 +00:00
filesystems Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2011-12-01 08:28:53 -08:00
firmware_class
frv doc: fix broken references 2011-09-27 18:08:04 +02:00
hid HID: Move hiddev.txt to the new Documentation/hid directory 2011-03-22 11:43:51 +01:00
hwmon hwmon: (w83627ehf) Add support for the W83627UHG 2011-11-04 12:00:48 +01:00
i2c i2c: Fix device name for 10-bit slave address 2011-11-23 11:33:07 +01:00
i2o doc: i2o: fix typo 'Settting' 2011-06-07 16:06:01 +02:00
ia64 Fix common misspellings 2011-03-31 11:26:23 -03:00
ide
infiniband
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2011-10-27 08:44:20 +02:00
ioctl ioctl: register LTTng ioctl 2011-09-12 11:50:56 -07:00
isdn doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
ja_JP Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2011-07-25 23:06:24 -07:00
kbuild doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
kdump kdump: update kexec-tools URL and Vivek's email 2010-11-25 14:36:38 +01:00
ko_KR Docs/Kconfig: Update: osdl.org -> linuxfoundation.org 2010-11-15 23:50:13 +01:00
laptops Documentation: thinkpad-acpi grammo fixes 2011-11-04 12:01:47 -07:00
leds Documentation: fix leds-class.txt duplicated word 2011-11-04 12:01:48 -07:00
m68k Documentation: add pointer to name_to_dev_t for root= values 2011-08-03 14:25:21 -10:00
make kbuild: introduce HDR_ARCH_LIST for headers_install_all 2010-12-14 22:16:19 +01:00
mips Fix common misspellings 2011-03-31 11:26:23 -03:00
misc-devices Fix common misspellings 2011-03-31 11:26:23 -03:00
mmc mmc: core: Use delayed work in clock gating framework 2012-01-11 23:58:41 -05:00
mn10300
mtd
namespaces
netlabel
networking ipv4:correct description for tcp_max_syn_backlog 2011-12-06 13:02:28 -05:00
nfc NFC: Driver for NXP Semiconductors PN544 NFC chip. 2011-01-13 08:03:19 -08:00
parisc
PCI doc: fix broken references 2011-09-27 18:08:04 +02:00
pcmcia
power PM / Sleep: Update documentation related to system wakeup 2011-11-28 22:14:45 +01:00
powerpc Fix common misspellings 2011-03-31 11:26:23 -03:00
pps pps: add parallel port PPS signal generator 2011-01-13 08:03:21 -08:00
prctl
pti Kernel documentation for the PTI feature. 2011-05-13 16:31:00 -07:00
ptp ptp: Added a brand new class driver for ptp clocks. 2011-05-23 13:01:00 -07:00
rapidio RapidIO: documentation update 2011-11-02 16:07:02 -07:00
RCU rcu: Document interpretation of RCU-lockdep splats 2011-09-28 21:38:28 -07:00
s390 [S390] remove tape block docu 2011-07-24 10:48:22 +02:00
scheduler sched: Add documentation for bandwidth control 2011-08-14 12:03:58 +02:00
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2011-10-28 16:44:18 -07:00
security doc: fix broken references 2011-09-27 18:08:04 +02:00
serial RS485: fix inconsistencies in the meaning of some variables 2011-11-15 12:13:44 -08:00
sh sh: clkfwk: Kill off unused clk_set_rate_ex(). 2010-11-15 18:25:12 +09:00
sound Merge branch 'fix/asoc' into for-linus 2011-12-06 13:22:28 +01:00
sparc
spi doc: fix broken references 2011-09-27 18:08:04 +02:00
sysctl kernel/sysctl.c: add cap_last_cap to /proc/sys/kernel 2011-10-31 17:30:53 -07:00
target [SCSI] tcm_mod_builder.py: Fix generated *_drop_nodeacl() handler 2011-03-23 11:36:45 -05:00
telephony Fix common misspellings 2011-03-31 11:26:23 -03:00
thermal thermal: Add event notification to thermal framework 2011-01-12 00:08:35 -05:00
timers doc: fix broken references 2011-09-27 18:08:04 +02:00
trace mm: change isolate mode from #define to bitwise type 2011-10-31 17:30:44 -07:00
usb USB: linux-cdc-acm.inf: add support for the acm_ms gadget 2011-11-29 09:59:29 +09:00
vDSO Document the vDSO and add a reference parser 2011-07-14 17:57:09 -07:00
video4linux [media] gspca - zc3xx: New webcam 03f0:1b07 HP Premium Starter Cam 2011-09-23 23:31:12 -03:00
virtual Merge branch 'for-linus' of git://github.com/richardweinberger/linux 2011-11-02 09:45:39 -07:00
vm Merge branches 'slab/next' and 'slub/partial' into slab/for-linus 2011-10-26 18:09:12 +03:00
w1 Fix common misspellings 2011-03-31 11:26:23 -03:00
watchdog Documentation: watchdog: add guide how to convert drivers to new framework 2011-11-05 21:25:16 +01:00
wimax
x86 x86-64, doc: Remove int 0xcc from entry_64.S documentation 2011-08-16 08:04:08 -07:00
zh_CN remove the messy code file Documentation/zh_CN/SubmitChecklist 2011-09-26 16:18:41 -07:00
.gitignore
00-INDEX Documentation: add Ramoops usage description 2011-08-13 18:34:03 -07:00
applying-patches.txt
atomic_ops.txt Documentation/atomic_ops.txt: avoid volatile in sample code 2011-05-26 17:12:34 -07:00
bad_memory.txt
basic_profiling.txt
binfmt_misc.txt
braille-console.txt
bt8xxgpio.txt
btmrvl.txt
BUG-HUNTING
bus-virt-phys-mapping.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
cachetlb.txt mm: convert mm->cpu_vm_cpumask into cpumask_var_t 2011-05-25 08:39:21 -07:00
Changes Documentation/Changes: remove some really obsolete text 2011-07-11 16:48:38 -07:00
circular-buffers.txt
coccinelle.txt scripts/coccinelle: update for compatability with Coccinelle 0.2.4 2010-12-03 12:27:01 +01:00
CodingStyle Documentation: update CodingStyle use of braces 2011-11-04 12:01:47 -07:00
cpu-hotplug.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
cpu-load.txt
cputopology.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
devices.txt Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2010-10-28 09:35:11 -07:00
DMA-API-HOWTO.txt Documentation/DMA-API-HOWTO.txt: fix misleading example 2011-07-26 16:49:45 -07:00
DMA-API.txt include/linux/dma-mapping.h: add dma_zalloc_coherent() 2011-11-02 16:07:02 -07:00
DMA-attributes.txt
DMA-ISA-LPC.txt
dmaengine.txt Improve slave/cyclic DMA engine documentation 2011-07-27 20:33:48 +05:30
dontdiff Documentation: update dontdiff file 2011-05-23 15:14:11 -07:00
dynamic-debug-howto.txt Merge branch 'docs-next' of git://git.lwn.net/linux-2.6 2011-03-27 19:46:59 -07:00
edac.txt Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
eisa.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
email-clients.txt Documentation: email-clients: Add better Thunderbird information 2011-08-13 18:34:03 -07:00
feature-removal-schedule.txt sysctl: make CONFIG_SYSCTL_SYSCALL default to n 2011-11-02 16:07:02 -07:00
flexible-arrays.txt flex_array: flex_array_prealloc takes a number of elements, not an end 2011-04-28 16:12:47 -04:00
futex-requeue-pi.txt
gcov.txt
gpio.txt Revert "gpiolib: annotate gpio-intialization with __must_check" 2011-01-13 17:26:46 -08:00
highuid.txt
HOWTO Documentation: update LXR web link 2011-05-23 15:14:11 -07:00
hw_random.txt
hwspinlock.txt hwspinlock/core: register a bank of hwspinlocks in a single API call 2011-09-21 19:45:34 +03:00
init.txt
initrd.txt
Intel-IOMMU.txt
intel_txt.txt
io-mapping.txt
io_ordering.txt
iostats.txt Documentation/iostats.txt: bit-size reference etc. 2011-03-23 20:44:18 +01:00
IPMI.txt IPMI: Add the document description of ipmi_get_smi_info 2010-12-14 00:22:00 -05:00
IRQ-affinity.txt bitmap, irq: add smp_affinity_list interface to /proc/irq 2011-05-25 08:39:45 -07:00
IRQ.txt
irqflags-tracing.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
isapnp.txt
java.txt
kernel-doc-nano-HOWTO.txt
kernel-docs.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
kernel-parameters.txt Merge branch 'iommu/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu 2011-12-09 08:08:14 -08:00
kmemcheck.txt
kmemleak.txt Documentation: update kmemleak supported archs 2011-06-15 21:52:50 -07:00
kobject.txt
kprobes.txt tree-wide: fix comment/printk typos 2010-11-01 15:38:34 -04:00
kref.txt kref: Fix typo in kref documentation 2011-03-07 13:20:05 -08:00
ldm.txt
local_ops.txt
lockdep-design.txt
lockstat.txt Documentation: Add statistics about nested locks 2011-05-28 17:03:29 +02:00
logo.gif
logo.txt
magic-number.txt doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
Makefile [media] Remove the old V4L1 v4lgrab.c file 2010-12-29 08:17:12 -02:00
ManagementStyle
mca.txt doc: fix wrong arch/i386 references 2011-06-13 13:43:05 +02:00
md.txt md: update documentation for md/rdev/state sysfs interface 2011-07-28 11:31:48 +10:00
media-framework.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
memory-barriers.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
memory-hotplug.txt memory hotplug: Allow memory blocks to span multiple memory sections 2011-02-03 16:08:57 -08:00
memory.txt
mono.txt
mutex-design.txt
nmi_watchdog.txt
nommu-mmap.txt
numastat.txt
oops-tracing.txt module,bug: Add TAINT_OOT_MODULE flag for modules not built in-tree 2011-11-07 07:54:42 +10:30
padata.txt
parport-lowlevel.txt
parport.txt
pi-futex.txt
pinctrl.txt drivers: create a pin control subsystem 2011-10-13 12:49:17 +02:00
pnp.txt
preempt-locking.txt
printk-formats.txt Documentation: update printk-formats.txt 2011-06-15 21:52:50 -07:00
prio_tree.txt
ramoops.txt Documentation: add Ramoops usage description 2011-08-13 18:34:03 -07:00
rbtree.txt Documentation: Update augmented rbtree documentation 2011-07-24 10:03:05 -07:00
rfkill.txt doc: fix broken references 2011-09-27 18:08:04 +02:00
robust-futex-ABI.txt
robust-futexes.txt
rt-mutex-design.txt
rt-mutex.txt
rtc.txt RTC: Fix up rtc.txt documentation to reflect changes to generic rtc layer 2011-03-09 11:25:10 -08:00
SAK.txt
SecurityBugs Fix common misspellings 2011-03-31 11:26:23 -03:00
serial-console.txt
sgi-ioc4.txt
sgi-visws.txt
SM501.txt
sparse.txt
spinlocks.txt Documentation/spinlocks.txt: Remove reference to sti()/cli() 2011-07-11 12:45:04 -07:00
stable_api_nonsense.txt doc: stable_api_nonsense.txt: fix paragraph to make more sense. 2011-03-30 12:02:05 +02:00
stable_kernel_rules.txt Update email address for stable patch submission 2011-10-18 13:58:59 -07:00
SubmitChecklist Documentation/SubmitChecklist: add RCU debug config options 2011-07-25 20:57:17 -07:00
SubmittingDrivers Documentation: SubmittingDrivers: fix Linus's git tree URL 2011-08-13 18:34:03 -07:00
SubmittingPatches Documentation: fix spelling error in SubmittingPatches 2011-08-13 18:34:02 -07:00
svga.txt
sysfs-rules.txt
sysrq.txt
unaligned-memory-access.txt
unicode.txt
unshare.txt
VGA-softcursor.txt
vgaarbiter.txt Documentation: fix vgaarbiter.txt typos etc. 2011-05-23 15:14:11 -07:00
video-output.txt
volatile-considered-harmful.txt
workqueue.txt workqueue: Document debugging tricks 2011-03-31 13:40:42 +02:00
xz.txt decompressors: add XZ decompressor module 2011-01-13 08:03:24 -08:00
zorro.txt