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ed88bae691
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Trent Piepho ed88bae691 leds: Add options to have GPIO LEDs start on or keep their state 
There already is a "default-on" trigger but there are problems with it.

For one, it's a inefficient way to do it and requires led trigger support
to be compiled in.

But the real reason is that is produces a glitch on the LED.  The GPIO is
allocate with the LED *off*, then *later* when the trigger runs it is
turned back on.  If the LED was already on via the GPIO's reset default or
action of the firmware, this produces a glitch where the LED goes from on
to off to on.  While normally this is fast enough that it wouldn't be
noticeable to a human observer, there are still serious problems.

One is that there may be something else on the GPIO line, like a hardware
alarm or watchdog, that is fast enough to notice the glitch.

Another is that the kernel may panic before the LED is turned back on, thus
hanging with the LED in the wrong state.  This is not just speculation, but
actually happened to me with an embedded system that has an LED which
should turn off when the kernel finishes booting, which was left in the
incorrect state due to a bug in the OF LED binding code.

We also let GPIO LEDs get their initial value from whatever the current
state of the GPIO line is.  On some systems the LEDs are put into some
state by the firmware or hardware before Linux boots, and it is desired to
have them keep this state which is otherwise unknown to Linux.

This requires that the underlying GPIO driver support reading the value of
output GPIOs.  Some drivers support this and some do not.

The platform device binding gains a field in the platform data
"default_state" that controls this.  There are three constants defined to
select from on, off, or keeping the current state.  The OpenFirmware
binding uses a property named "default-state" that can be set to "on",
"off", or "keep".  The default if the property isn't present is off.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
2009-06-23 20:21:39 +01:00
..
ABI Merge git://git.infradead.org/mtd-2.6 2009-06-22 16:56:22 -07:00
accounting Documentation/accounting/getdelays.c intialize the variable before using it 2009-06-16 19:47:51 -07:00
acpi ACPI: update debug parameter documentation 2008-11-07 21:45:29 -05:00
aoe aoe: user can ask driver to forget previously detected devices 2008-02-08 09:22:31 -08:00
arm [ARM] S3C24XX: GPIO: Change to macros for GPIO numbering 2009-05-18 16:26:03 +01:00
auxdisplay .gitignore updates 2008-10-30 11:38:45 -07:00
blackfin Blackfin arch: Add document about bfin-gpio 2009-01-07 23:14:38 +08:00
block trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
blockdev mflash: initial support 2009-04-07 08:12:38 +02:00
cdrom debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
cgroups memcg: add interface to reset limits 2009-06-18 13:03:48 -07:00
connector Documentation/connector/cn_test.c comment unused cn_test_want_notify() 2009-06-18 13:03:46 -07:00
console
cpu-freq [CPUFREQ] minor correction to cpu-freq documentation 2009-06-15 11:49:42 -04:00
cpuidle cpuidle: Add Documentation 2008-02-14 00:16:13 -05:00
cris fix random typos 2008-10-16 11:21:30 -07:00
crypto async_tx, dmaengine: document channel allocation and api rework 2009-01-05 18:10:19 -07:00
development-process docs: Encourage better changelogs in the development process document 2009-06-04 10:32:49 -06:00
device-mapper dm crypt: add documentation 2008-04-25 13:27:03 +01:00
DocBook debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
driver-model Driver Core: Warn driver authors about adding device attributes 2009-06-15 21:30:23 -07:00
dvb V4L/DVB (11962): dvb: Fix broken link in get_dvb_firmware for nxt2004 (A180) 2009-06-16 19:07:39 -03:00
early-userspace Documentation: Remove last references to BitKeeper. 2008-04-21 22:19:05 +00:00
fault-injection debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
fb Documentation/fb/vesafb.txt: fix typo 2009-06-16 19:47:58 -07:00
filesystems Merge branch 'for-2.6.31' of git://fieldses.org/git/linux-nfsd 2009-06-22 12:55:50 -07:00
firmware_class driver core: fix documentation of request_firmware_nowait 2009-06-15 21:30:24 -07:00
frv move frv docs one level up 2008-02-03 15:54:28 +02:00
hwmon hwmon: (f71882fg) Add support for the F71858F 2009-06-15 18:39:52 +02:00
i2c i2c: Add a sysfs interface to instantiate devices 2009-06-19 16:58:20 +02:00
i2o
ia64 trivial: Fix misspelling of firmware 2009-03-30 15:21:59 +02:00
ide ide: preserve Host Protected Area by default (v2) 2009-06-07 13:52:52 +02:00
infiniband IPoIB: Document newish features 2009-04-08 13:52:01 -07:00
input Merge commit 'v2.6.30' into next 2009-06-11 01:58:01 -07:00
ioctl LinuxPPS: core support 2009-06-18 13:04:04 -07:00
isdn isdn: clean up documentation index 2009-06-20 01:10:38 -07:00
ja_JP block: rename CONFIG_LBD to CONFIG_LBDAF 2009-06-19 08:08:50 +02:00
kbuild kconfig: resort the documentation of the environment variables 2009-06-09 22:37:47 +02:00
kdump trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
ko_KR
laptops trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
lguest lguest: add support for indirect ring entries 2009-06-12 22:27:13 +09:30
m68k
make
mips ide: remove unused CONFIG_BLK_DEV_IDE_AU1XXX_SEQTS_PER_RQ 2009-01-14 19:19:03 +01:00
misc-devices drivers/misc/isl29003.c: driver for the ISL29003 ambient light sensor 2009-04-01 08:59:18 -07:00
mn10300 trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
mtd trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
namespaces
netlabel
networking Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6 2009-06-15 03:02:23 -07:00
parisc
PCI PCI AER: software error injection 2009-06-16 14:30:14 -07:00
pcmcia .gitignore updates 2008-10-30 11:38:45 -07:00
power Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-06-14 13:46:25 -07:00
powerpc leds: Add options to have GPIO LEDs start on or keep their state 2009-06-23 20:21:39 +01:00
pps LinuxPPS: core support 2009-06-18 13:04:04 -07:00
prctl generic, x86: add tests for prctl PR_GET_TSC and PR_SET_TSC 2008-04-19 19:19:55 +02:00
RCU trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
s390 trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
scheduler trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2009-06-17 09:50:44 -07:00
serial Create/use more directory structure in the Documentation/ tree. 2008-11-14 17:28:53 +00:00
sh sh: Kill off remaining CONFIG_SH_KGDB bits. 2008-12-22 18:44:05 +09:00
sound Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6 2009-06-21 13:13:08 -07:00
sparc sparc: Remove Documentation/sparc/sbus_drivers.txt 2008-08-29 02:15:25 -07:00
spi spi: documentation: emphasise spi_master.setup() semantics 2009-04-21 13:41:50 -07:00
sysctl vmscan: properly account for the number of page cache pages zone_reclaim() can reclaim 2009-06-16 19:47:45 -07:00
telephony remove mention of CONFIG_KMOD from documentation 2008-07-22 19:24:29 +10:00
thermal thermal: update the documentation 2008-04-29 02:49:47 -04:00
timers trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
trace debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
uml
usb trivial: usb: fix missing space typo in doc 2009-06-12 18:01:51 +02:00
video4linux V4L/DVB (11996): saa7134: add support for AVerMedia M103 (f736) 2009-06-16 19:07:53 -03:00
vm Documentation/vm/Makefile: don't try to build slqbinfo 2009-06-17 09:45:46 -07:00
w1 w1: send status messages after command processing 2009-01-08 08:31:14 -08:00
watchdog [WATCHDOG] hpwdt: Add NMI sourcing 2009-06-18 07:32:06 +00:00
wimax i2400m: documentation and instructions for usage 2009-01-07 10:00:18 -08:00
x86 Merge branch 'linus' into x86/mce3 2009-06-11 23:31:52 +02:00
zh_CN Chinese: add translation of Codingstyle 2008-01-24 20:40:04 -08:00
00-INDEX trivial: fix where cgroup documentation is not correctly referred to 2009-03-30 15:22:02 +02:00
applying-patches.txt
atomic_ops.txt Documentation/atomic_ops.txt: fix sample code 2009-06-16 19:47:52 -07:00
bad_memory.txt Document handling of bad memory 2008-12-03 16:09:53 -07:00
basic_profiling.txt
binfmt_misc.txt
braille-console.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
bt8xxgpio.txt gpio: add bt8xxgpio driver 2008-07-25 10:53:30 -07:00
BUG-HUNTING Documentation: add hint about call traces & module symbols to BUG-HUNTING 2008-02-06 10:41:09 -08:00
c2port.txt Add c2 port support 2008-11-12 17:17:18 -08:00
cachetlb.txt
Changes Documentation/Changes: perl is needed to build the kernel 2009-06-18 13:03:46 -07:00
CodingStyle trivial: fix typo milisecond/millisecond for documentation and source comments. 2009-06-12 18:01:46 +02:00
cpu-hotplug.txt x86: use possible_cpus=NUM to extend the possible cpus allowed 2008-12-18 12:08:05 +01:00
cpu-load.txt
cputopology.txt cpumask: Use topology_core_cpumask()/topology_thread_cpumask() 2009-01-11 19:12:49 +01:00
credentials.txt CRED: Documentation 2008-11-14 10:39:26 +11:00
dcdbas.txt
debugging-modules.txt Documentation: Clarify when module debugging actually works. 2008-02-03 15:27:38 +02:00
debugging-via-ohci1394.txt firewire: fw-ohci: add option for remote debugging 2008-04-18 17:55:33 +02:00
dell_rbu.txt trivial: Documentation/dell_rbu.txt: fix typos 2009-06-12 18:01:50 +02:00
devices.txt lanana: assign a device name and numbering for MAX3100 2009-04-07 08:44:05 -07:00
DMA-API.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
DMA-attributes.txt powerpc/cell: Add DMA_ATTR_WEAK_ORDERING dma attribute and use in Cell IOMMU code 2008-07-22 10:39:36 +10:00
DMA-ISA-LPC.txt
DMA-mapping.txt dma-mapping: update the old macro DMA_nBIT_MASK related documentations 2009-04-07 08:31:12 -07:00
dmaengine.txt async_tx, dmaengine: document channel allocation and api rework 2009-01-05 18:10:19 -07:00
dontdiff dontdiff: Fix asm exclude 2009-03-26 15:45:43 -07:00
dynamic-debug-howto.txt Dynamic debug: allow simple quoting of words 2009-03-24 16:38:27 -07:00
edac.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
eisa.txt
email-clients.txt Documentation/email-clients.txt: add some info about gmail 2008-11-06 15:41:19 -08:00
exception.txt
feature-removal-schedule.txt i2c: Get rid of the legacy binding model 2009-06-19 16:58:18 +02:00
futex-requeue-pi.txt futex: add requeue-pi documentation 2009-05-09 07:12:50 +02:00
gcov.txt gcov: add gcov profiling infrastructure 2009-06-18 13:03:57 -07:00
gpio.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
highuid.txt [SPARC]: Remove SunOS and Solaris binary support. 2008-04-21 15:10:15 -07:00
HOWTO Remove Andrew Morton's http://www.zip.com.au/~akpm/ 2008-10-16 11:21:32 -07:00
hw_random.txt hw_random doc updates 2008-03-24 19:22:19 -07:00
ics932s401 ics932s401: new clock generator chip driver 2008-11-12 17:17:18 -08:00
initrd.txt use the newc archive format as requested by initramfs 2008-02-03 14:54:41 +02:00
Intel-IOMMU.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
io_ordering.txt
io-mapping.txt io mapping: improve documentation 2008-11-03 18:21:44 +01:00
IO-mapping.txt Documentation: move DMA-mapping.txt to Doc/PCI/ 2009-01-29 18:19:29 -08:00
iostats.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
IPMI.txt
IRQ-affinity.txt genirq: Expose default irq affinity mask (take 3) 2008-06-05 15:18:30 +02:00
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt
kernel-doc-nano-HOWTO.txt kernel-doc: restrict syntax for private: and public: 2009-05-02 15:36:10 -07:00
kernel-docs.txt doc: update to URL and status of kernel-docs.txt entry 2008-06-06 11:29:10 -07:00
kernel-parameters.txt Merge git://git.infradead.org/~dwmw2/iommu-2.6.31 2009-06-22 21:38:22 -07:00
keys-request-key.txt keys: allow the callout data to be passed as a blob rather than a string 2008-04-29 08:06:16 -07:00
keys.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
kmemcheck.txt kmemcheck: add the kmemcheck documentation 2009-06-13 14:27:20 +02:00
kmemleak.txt kmemleak: Add documentation on the memory leak detector 2009-06-11 17:03:29 +01:00
kobject.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
kprobes.txt debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. 2009-06-15 21:30:28 -07:00
kref.txt docs: convert kref semaphore to mutex 2008-02-06 10:41:09 -08:00
ldm.txt
leds-class.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
leds-lp3944.txt leds: LED driver for National Semiconductor LP3944 Funlight Chip 2009-06-23 20:21:38 +01:00
local_ops.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
lockdep-design.txt locking: Documentation: lockdep-design.txt, fix note of state bits 2009-04-26 18:21:24 +02:00
lockstat.txt lockstat: contend with points 2008-10-20 15:43:10 +02:00
logo.gif Revert "linux.conf.au 2009: Tuz" 2009-04-27 12:00:27 -07:00
logo.txt Revert "linux.conf.au 2009: Tuz" 2009-04-27 12:00:27 -07:00
magic-number.txt documentation: update header file paths 2009-01-06 15:59:28 -08:00
Makefile docsrc: build Documentation/ sources 2008-08-12 16:07:30 -07:00
ManagementStyle docs: fix ManagementStyle book name 2008-10-30 11:38:46 -07:00
markers.txt markers: comment marker_synchronize_unregister() on data dependency 2008-11-28 16:47:41 +01:00
mca.txt The ps2esdi driver was marked as BROKEN more than two years ago due to being 2008-03-17 09:03:05 +01:00
md.txt Documentation/md.txt update 2009-03-31 15:18:37 +11:00
memory-barriers.txt sched: Document memory barriers implied by sleep/wake-up primitives 2009-04-29 14:15:55 +02:00
memory-hotplug.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
memory.txt
mono.txt
mutex-design.txt
nmi_watchdog.txt x86, nmi-watchdog: update procfs nmi_watchdog file documentation v2 2008-10-30 19:07:04 +01:00
nommu-mmap.txt NOMMU: Make mmap allocation page trimming behaviour configurable. 2009-01-08 12:04:47 +00:00
numastat.txt
oops-tracing.txt Taint kernel after WARN_ON(condition) 2008-04-29 08:05:59 -07:00
parport-lowlevel.txt
parport.txt
pi-futex.txt
pnp.txt Documentation: Replace obsolete "driverfs" with "sysfs". 2008-01-24 20:40:04 -08:00
preempt-locking.txt
printk-formats.txt DOC: add printk-formats.txt 2008-11-12 17:17:17 -08:00
prio_tree.txt
rbtree.txt trivial: rbtree.txt: fix rb_entry() parameters in sample code 2009-06-12 18:01:47 +02:00
rfkill.txt rfkill: export persistent attribute in sysfs 2009-06-19 11:50:18 -04:00
robust-futex-ABI.txt futex: documentation: fix inconsistent description of futex list_op_pending 2009-06-18 13:03:56 -07:00
robust-futexes.txt
rt-mutex-design.txt
rt-mutex.txt
rtc.txt rtc: cleanup example code 2008-02-06 10:41:14 -08:00
SAK.txt Remove Andrew Morton's old email accounts 2008-10-16 11:21:32 -07:00
SecurityBugs
SELinux.txt selinux: add support for installing a dummy policy (v2) 2008-08-27 08:54:08 +10:00
serial-console.txt
sgi-ioc4.txt
sgi-visws.txt
slow-work.txt Document the slow work thread pool 2009-04-03 16:42:35 +01:00
SM501.txt trivial: Miscellaneous documentation typo fixes 2009-06-12 18:01:47 +02:00
Smack.txt smack: implement logging V3 2009-04-14 09:00:23 +10:00
sparse.txt Documentation: explain the difference between __bitwise and __bitwise__ 2009-04-11 08:18:11 +02:00
spinlocks.txt Add additional examples in Documentation/spinlocks.txt 2008-04-11 13:21:14 -06:00
stable_api_nonsense.txt
stable_kernel_rules.txt Update stable tree documentation 2008-10-29 15:03:49 -07:00
SubmitChecklist block: rename CONFIG_LBD to CONFIG_LBDAF 2009-06-19 08:08:50 +02:00
SubmittingDrivers Remove Andrew Morton's old email accounts 2008-10-16 11:21:32 -07:00
SubmittingPatches Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-06-14 13:46:25 -07:00
svga.txt
sysfs-rules.txt Doc/sysfs-rules: Swap the order of the words so the sentence makes more sense 2009-05-08 19:22:20 -07:00
sysrq.txt Merge branch 'tracing/core-v2' into tracing-for-linus 2009-04-02 00:49:02 +02:00
tomoyo.txt tomoyo: add Documentation/tomoyo.txt 2009-04-14 09:14:58 +10:00
unaligned-memory-access.txt introduce HAVE_EFFICIENT_UNALIGNED_ACCESS Kconfig symbol 2008-07-25 10:53:27 -07:00
unicode.txt
unshare.txt
VGA-softcursor.txt
video-output.txt
volatile-considered-harmful.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
voyager.txt
zorro.txt