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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>
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WARNING: drivers/leds/leds-gpio.o(.text+0x153): Section mismatch in reference from the function gpio_led_probe() to the function .devinit.text:create_gpio_led()
The function gpio_led_probe() references the function __devinit
create_gpio_led(). This is often because gpio_led_probe lacks a __devinit
annotation or the annotation of create_gpio_led is wrong.
Signed-off-by: Zhenwen Xu <helight.xu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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Fix build problems with leds-gpio:
CC drivers/leds/leds-gpio.o
drivers/leds/leds-gpio.c: In function 'create_gpio_led':
drivers/leds/leds-gpio.c:85: warning: 'return' with no value, in function returning non-void
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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Sometimes it's awkward to make sure that the array in the
platform_data handed to the leds-gpio driver has only valid
data ... some leds may not be always available, and coping
with that currently requires patching or rebuilding the array.
This patch fixes that by making it be OK to pass an invalid
GPIO (such as "-EINVAL") ... such table entries are skipped.
[rpurdie@linux.intel.com: adjusted to apply against other led tree changes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Tested-by: Diego Dompe <diego.dompe@ridgerun.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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Add an option to preserve LED state when suspending/resuming to the LED
gpio driver. Based on a suggestion from Robert Jarzmik.
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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You can't have multiple module_init()/module_exit calls so resort to messy
ifdefs potentially pending some code refactoring.
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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Add bindings to support LEDs defined as of_platform devices in addition to
the existing bindings for platform devices.
New options in Kconfig allow the platform binding code and/or the
of_platform code to be turned on. The of_platform code is of course only
available on archs that have OF support.
The existing probe and remove methods are refactored to use new functions
create_gpio_led(), to create and register one led, and delete_gpio_led(),
to unregister and free one led. The new probe and remove methods for the
of_platform driver can then share most of the common probe and remove code
with the platform driver.
The suspend and resume methods aren't shared, but they are very short. The
actual led driving code is the same for LEDs created by either binding.
The OF bindings are based on patch by Anton Vorontsov
<avorontsov@ru.mvista.com>. They have been extended to allow multiple LEDs
per device.
Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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Add suspend/resume to the core class and remove all the now unneeded
code from various drivers. Originally the class code couldn't support
suspend/resume but since class_device can there is no reason for
each driver doing its own suspend/resume anymore.
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Enhance leds-gpio to provide hardware-based led flashing by passing
through the blink_set() call to a optionally set platform-specific
function pointer.
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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Since 43cc71eed1250755986da4c0f9898f9a635cb3bf, the platform
modalias is prefixed with "platform:". Add MODULE_ALIAS() to the
hotpluggable platform LED drivers, to re-enable auto loading.
[dbrownell@users.sourceforge.net: more drivers, registration fixes]
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It appears that we can't just check to see if we're in a task
context ... so instead of trying that, just make the relevant
leds always schedule a little worklet.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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Call gpio_cansleep only after gpio_request succeeded avoiding an
oops.
Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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When gpio_direction_output() is called, led_dat->active_low is used
as default value. This means that the led will always be off by
default. cdev.brightness should really have been set to LED_OFF
unconditionally to reflect this behavior.
Signed-off-by: Raphael Assenat <raph@8d.com>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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Three bugfixes to the leds-gpio driver, plus minor whitespace tweaks:
- Do the INIT_WORK() before registering each LED, so if its trigger
becomes immediately active it can schedule work without oopsing..
- Use normal registration, not platform_driver_probe(), so that
devices appearing "late" (hotplug type) can still be bound.
- Mark the driver remove code as "__devexit", preventing oopses
when the underlying device is removed.
These issues came up when using this driver with some GPIO expanders
living on serial busses, which act unlike "normal" platform devices:
they can appear and vanish along with the serial bus driver.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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Teach the new leds-gpio driver that some GPIOs can't be accessed from
timer callbacks ... which is how all today's standard triggers use them.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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This patch adds support for GPIO connected leds via the new GPIO framework.
Information about leds (gpio, polarity, name, default trigger) is passed
to the driver via platform_data.
Signed-off-by: Raphael Assenat <raph@8d.com>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
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