This add basic led support for Freescale MC13783 PMIC.
Signed-off-by: Philippe Rétornaz <philippe.retornaz@epfl.ch>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
In current implementation, if device_create_file failed in register_nasgpio_led,
led_classdev_unregister will be executed twice.
( in register_nasgpio_led it calls led_classdev_unregister before return and in nas_gpio_init out_err )
This patch fixes it by only unregistering those that were successfully registered in out_err.
( not including last failed register_nasgpio_led call )
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Dave Hansen <dave@sr71.net>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
In current implementation, lp3944_probe return 0 even if lp3944_configure fail.
Therefore, led_classdev_unregister will be executed twice
( in error handling of lp3944_configure and lp3944_remove ).
This patch properly handles lp3944_configure fail in lp3944_probe.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
max_brightness is not writable, thus set permissions to 0444.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The leds-gpio blink_set() callback follows the same prototype as the
main leds subsystem blink_set() one.
The problem is that to stop blink, normally, a leds driver does it
in the brightness_set() callback when asked to set a new fixed value.
However, with leds-gpio, the platform has no hook to do so, as this
later callback results in a standard GPIO manipulation.
This changes the leds-gpio specific callback to take a new argument
that indicates whether the LED should be blinking or not and in what
state it should be set if not. We also update the dns323 platform
which seems to be the only user of this so far.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
It is based on the previously submitted code by Alessandro Zummo, but is
changed to use the new GPIO driver with 2.6.33, and the driver has been
moved to drivers/leds where it belongs.
[akpm@linux-foundation.org: coding-style fixes]
[randy.dunlap@oracle.com: fix net5501 kconfig]
Signed-off-by: Bjarke Istrup Pedersen <gurligebis@gentoo.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Improve device and platform data checks in probe function.
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
.name, .match_table and .owner are duplicated in both of_platform_driver
and device_driver. This patch is a removes the extra copies from struct
of_platform_driver and converts all users to the device_driver members.
This patch is a pretty mechanical change. The usage model doesn't change
and if any drivers have been missed, or if anything has been fixed up
incorrectly, then it will fail with a compile time error, and the fixup
will be trivial. This patch looks big and scary because it touches so
many files, but it should be pretty safe.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
The following structure elements duplicate the information in
'struct device.of_node' and so are being eliminated. This patch
makes all readers of these elements use device.of_node instead.
(struct of_device *)->node
(struct dev_archdata *)->prom_node (sparc)
(struct dev_archdata *)->of_node (powerpc & microblaze)
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
If we were to dynamically register/unregister leds and have udev or other
daemons handle the leds class uevents, we would be notified of the adding of a
new LED and if the daemon immediately tries to open one of the attributes of
the led device, it would fail with a "no such file or directory" error since
this the attributes are not yet created. Fix this by switching attributes to be
class-wide, such that the driver core will register these attributes with
device_add_attrs and then emit the kobject_uevent ADD signal.
Signed-off-by: Fainelli <ffainelli@freebox.fr>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The driver wrongly sets default state for LEDs that don't specify
default-state property.
Currently the driver handles default state this way:
memset(&led, 0, sizeof(led));
for_each_child_of_node(np, child) {
state = of_get_property(child, "default-state", NULL);
if (state) {
if (!strcmp(state, "keep"))
led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
...
}
ret = create_gpio_led(&led, ...);
}
Which means that all LEDs that do not specify default-state will inherit
the last value of the default-state property, which is wrong.
This patch fixes the issue by moving LED's template initialization into
the loop body.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This patch adds an LED driver to support the Dell Activity LED on the
Dell Latitude 2100 netbook and future products to come. The Activity LED
is visible externally in the lid so classroom instructors can observe it
from a distance. The driver uses the sysfs led_class and provides a
standard LED interface.
Signed-off by: Bob Rodgers <Robert_Rodgers@dell.com>
Signed-off-by: Louis Davis <Louis_Davis@dell.com>
Signed-off-by: Jim Dailey <Jim_Dailey@dell.com>, Developers
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Remove the need for "depends on LEDS_CLASS" by wrapping the affected
config options in an if/endif block. Similar for "depends on LEDS_TRIGGERS".
LEDS_COBALT_RAQ still has a "depends on LEDS_CLASS=y" since it cannot
be selected to build as a module.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
As each led device gets registered a kernel message gets printed. In
an embedded system with a number of leds this can produce a lot
of output that just looks like noise.
Change the message type to KERN_DEBUG since it might be useful
in the dmesg output "after" booting.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The id_table field of the struct pci_driver is constant in <linux/pci.h>
so it is worth to make pci_device_id also constant.
The semantic match that finds this kind of pattern is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r@
disable decl_init,const_decl_init;
identifier I1, I2, x;
@@
struct I1 {
...
const struct I2 *x;
...
};
@s@
identifier r.I1, y;
identifier r.x, E;
@@
struct I1 y = {
.x = E,
};
@c@
identifier r.I2;
identifier s.E;
@@
const struct I2 E[] = ... ;
@depends on !c@
identifier r.I2;
identifier s.E;
@@
+ const
struct I2 E[] = ...;
// </smpl>
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The ALIX2 LED driver and the CS5535 GPIO drivers share the same I/O
range which causes a conflict if they're both enabled. Fix this for now
by adding Kconfig dependencies. While at it, also drop the EXPERIMENTAL
flag, as the code has been around for awhile already.
Note that this is a hack. At some point, a real platform support for
this board should be added which handles the LEDs via the leds-gpio
driver.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Enable led sub device in Marvell 88PM860x. Two LED arrays can be supported.
Each LED array can be used for R,G,B leds.
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Currently the driver leds-pwm doesn't set max_brightness for the led device
although it's platform data proides a maximum brightness. Instead it stores its
own private driver struct. The max_brightness defaults to 255 for led device if
it has not been set.
As a result any leds-pwm device with a different maximum brightness will show
incorrect behavior, as it is posible to either set a longer then period duty
time or not be able to switch the led to full brightness.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This patch changes the default trigger from "ide-disk"
to "default-on". Users updating from kernels not having this
LED driver will prefer having the same LED behavior as they
used to.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
drivers/leds/leds-ss4200.c: In function 'ich7_lpc_probe':
drivers/leds/leds-ss4200.c:353: warning: 'return' with no value, in function returning non-void
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This driver provides an interface for controlling LEDs (or vibrators)
connected to PMICs for which there is a regulator framework driver.
This driver can be used, for instance, to control vibrator on all Motorola EZX
phones using the pcap-regulator driver services.
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Use resource_size() for ioremap.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Use resource_size() for ioremap.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The LT3593 is a step-up DC/DC converter designed to drive up to ten
white LEDs in series. The current flow can be set with a control pin.
This driver controls any number of such devices connected on generic
GPIOs and exports the function as as platform_driver.
The gpio_led platform data struct definition is reused for this purpose.
Successfully tested on a PXA embedded board.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
pci_enable_result is defined using the __must_check macro but
leds-ss4200 is not checking the return value.
Signed-off-by: Javier Martinez Canillas <martinez.javier@gmail.com>
Signed-off-by: Dave Hansen <dave@sr71.net>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This makes the LEDs driver for ALIX2.C boards work with Coreboot by
looking up the port address in the MSR rather than hard-coding it.
The BIOS scan also needed some tweaks as the string in Coreboot differs
from the one in the legacy BIOS.
Successfully tested with both the legacy tinyBIOS as well as Coreboot
v3.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This code is based on a driver that came in the "Open-source
and GPL components" download here:
http://downloadcenter.intel.com/SearchResult.aspx?lang=eng&ProductFamily=Server+Products&ProductLine=Intel%C2%AE+Storage+Systems&ProductProduct=Intel%C2%AE+Entry+Storage+System+SS4200-E&OSVersion=OS+Independent
It was in a file called nasgpio.c inside of a second zip file
called SS4200-E_Linux_SIO_Driver-v1.4.zip and is based on this
updated to use the LED subsystem with the ioctl and hardware
monitor support removed.
I don't have any need for brightness
control, and its code is *completely* separate from the on/off
controls implemented here. If anyone else wants it, I'd be
happy to look into adding it, but I don't care enough for now.
Except for the probe routines, I rewrote most of it. I also
Note that I don't have any hardware documentation except for
the original driver.
Thanks go to Arjan for his help in getting the original source
for this released and for chasing down some licensing issues.
Signed-off-by: Dave Hansen <dave@sr71.net>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Makes use of skip_spaces() defined in lib/string.c for removing leading
spaces from strings all over the tree.
It decreases lib.a code size by 47 bytes and reuses the function tree-wide:
text data bss dec hex filename
64688 584 592 65864 10148 (TOTALS-BEFORE)
64641 584 592 65817 10119 (TOTALS-AFTER)
Also, while at it, if we see (*str && isspace(*str)), we can be sure to
remove the first condition (*str) as the second one (isspace(*str)) also
evaluates to 0 whenever *str == 0, making it redundant. In other words,
"a char equals zero is never a space".
Julia Lawall tried the semantic patch (http://coccinelle.lip6.fr) below,
and found occurrences of this pattern on 3 more files:
drivers/leds/led-class.c
drivers/leds/ledtrig-timer.c
drivers/video/output.c
@@
expression str;
@@
( // ignore skip_spaces cases
while (*str && isspace(*str)) { \(str++;\|++str;\) }
|
- *str &&
isspace(*str)
)
Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
Cc: Julia Lawall <julia@diku.dk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: David Howells <dhowells@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If there are leds present in the OF tree, but the GPIOs for (some) of
them are unavailable, led_data doesn't get populated with correct
devices. Then, on device unbinding, one can crash the kernel.
Workaround this by setting led->gpio to invalid value early.
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Move the remaining headers under plat-omap/include/mach
to plat-omap/include/plat. Also search and replace the
files using these headers to include using the right path.
This was done with:
#!/bin/bash
mach_dir_old="arch/arm/plat-omap/include/mach"
plat_dir_new="arch/arm/plat-omap/include/plat"
headers=$(cd $mach_dir_old && ls *.h)
omap_dirs="arch/arm/*omap*/ \
drivers/video/omap \
sound/soc/omap"
other_files="drivers/leds/leds-ams-delta.c \
drivers/mfd/menelaus.c \
drivers/mfd/twl4030-core.c \
drivers/mtd/nand/ams-delta.c"
for header in $headers; do
old="#include <mach\/$header"
new="#include <plat\/$header"
for dir in $omap_dirs; do
find $dir -type f -name \*.[chS] | \
xargs sed -i "s/$old/$new/"
done
find drivers/ -type f -name \*omap*.[chS] | \
xargs sed -i "s/$old/$new/"
for file in $other_files; do
sed -i "s/$old/$new/" $file
done
done
for header in $(ls $mach_dir_old/*.h); do
git mv $header $plat_dir_new/
done
Signed-off-by: Tony Lindgren <tony@atomide.com>
The I2C_CLIENT_INSMOD_1 macro is only useful for i2c drivers which
implement device detection. The leds-pca9532 driver doesn't, so there
is no point in calling it.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Riku Voipio <riku.voipio@iki.fi>
This makes it consistent with other buses (platform, i2c, vio, ...). I'm
not sure why we use the prefixes, but there must be a reason.
This was easy enough to do it, and I did it.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Samuel Ortiz <sameo@openedhand.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Acked-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The serio ports on i8042 are not completely isolated; while we provide
enough locking to ensure proper serialization when accessing control
and data registers AUX and KBD ports can still have an effect on each
other on PS/2 protocol level. The most prominent effect is that
issuing a command for the device connected to one port may cause
abort of the command currently executing by the device connected to
another port.
Since i8042 nor serio subsystem are not aware of the details of the
PS/2 protocol (length of the commands and their replies and so on) the
locking should be done on libps2 level by adding special handling when
we see that we are dealing with serio port on i8042.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
A pointer to clevo_mail_led_probe is passed to the core via
platform_driver_register and so the function must not disappear when the
.init sections are discarded. Otherwise (if also having HOTPLUG=y)
unbinding and binding a device to the driver via sysfs will result in an
oops as does a device being registered late.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This is needed to get kde-powersave to work properly on some g4
powerbooks.
From: Olaf Hering <olh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: Samuel R. C. Vale <srcvale@holoscopio.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
The WM831x devices feature two software controlled status LEDs with
hardware assisted blinking.
The device can also autonomously control the LEDs based on a selection
of sources. This can be configured at boot time using either platform
data or the chip OTP. A sysfs file in the style of that for triggers
allowing the control source to be configured at run time. Triggers
can't be used here since they can't depend on the implementation details
of a specific LED type.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
If we change the inverted attribute to another value, the LED will not be
inverted until we change the GPIO state.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Cc: Samuel R. C. Vale <srcvale@holoscopio.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When setting the same GPIO number, multiple IRQ shared requests will be
done without freing the previous request. It will also try to free a
failed request or an already freed IRQ if 0 was written to the gpio file.
All these oops and leaks were fixed with the following solution: keep the
previous allocated GPIO (if any) still allocated in case the new request
fails. The alternative solution would desallocate the previous allocated
GPIO and set gpio as 0.
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: Samuel R. C. Vale <srcvale@holoscopio.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
Richard Purdie