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author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-07-01 19:09:11 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-07-01 19:09:11 -0700 |
commit | 13d45f79a2af84de9083310db58b309a61065208 (patch) | |
tree | 06968d83ed6e5e23e1f729cf6f096f9a79f14f72 /Documentation/leds/leds-class-flash.txt | |
parent | 05fde26a943a9c55d8b498d97bb49d3d207e5069 (diff) | |
parent | b67893206fc0a0e8af87130e67f3d8ae553fc87c (diff) |
Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds
Pull LED subsystem updates from Bryan Wu:
"In this cycle, we finished to merge patches for LED Flash class
driver.
Other than that we have some bug fixes and new drivers for LED
controllers"
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds: (33 commits)
leds:lp55xx: fix firmware loading error
leds: fix max77693-led build errors
leds: fix aat1290 build errors
leds: aat1290: pass flags parameter to devm_gpiod_get
leds: ktd2692: pass flags parameter to devm_gpiod_get
drivers/leds: don't use module_init in non-modular leds-cobalt-raq.c
leds: aat1290: add support for V4L2 Flash sub-device
DT: aat1290: Document handling external strobe sources
leds: max77693: add support for V4L2 Flash sub-device
media: Add registration helpers for V4L2 flash sub-devices
v4l: async: Add a pointer to of_node to struct v4l2_subdev, match it
Documentation: leds: Add description of v4l2-flash sub-device
leds: add BCM6358 LED driver
leds: add DT binding for BCM6358 LED controller
leds: fix brightness changing when software blinking is active
Documentation: leds-lp5523: describe master fader attributes
leds: lp5523: add master_fader support
leds: leds-gpio: Allow compile test if !GPIOLIB
leds: leds-gpio: Add missing #include <linux/of.h>
gpiolib: Add missing dummies for the unified device properties interface
...
Diffstat (limited to 'Documentation/leds/leds-class-flash.txt')
-rw-r--r-- | Documentation/leds/leds-class-flash.txt | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt index 19bb67355424..8da3c6f4b60b 100644 --- a/Documentation/leds/leds-class-flash.txt +++ b/Documentation/leds/leds-class-flash.txt @@ -20,3 +20,54 @@ Following sysfs attributes are exposed for controlling flash LED devices: - max_flash_timeout - flash_strobe - flash_fault + + +V4L2 flash wrapper for flash LEDs +================================= + +A LED subsystem driver can be controlled also from the level of VideoForLinux2 +subsystem. In order to enable this CONFIG_V4L2_FLASH_LED_CLASS symbol has to +be defined in the kernel config. + +The driver must call the v4l2_flash_init function to get registered in the +V4L2 subsystem. The function takes six arguments: +- dev : flash device, e.g. an I2C device +- of_node : of_node of the LED, may be NULL if the same as device's +- fled_cdev : LED flash class device to wrap +- iled_cdev : LED flash class device representing indicator LED associated with + fled_cdev, may be NULL +- ops : V4L2 specific ops + * external_strobe_set - defines the source of the flash LED strobe - + V4L2_CID_FLASH_STROBE control or external source, typically + a sensor, which makes it possible to synchronise the flash + strobe start with exposure start, + * intensity_to_led_brightness and led_brightness_to_intensity - perform + enum led_brightness <-> V4L2 intensity conversion in a device + specific manner - they can be used for devices with non-linear + LED current scale. +- config : configuration for V4L2 Flash sub-device + * dev_name - the name of the media entity, unique in the system, + * flash_faults - bitmask of flash faults that the LED flash class + device can report; corresponding LED_FAULT* bit definitions are + available in <linux/led-class-flash.h>, + * torch_intensity - constraints for the LED in TORCH mode + in microamperes, + * indicator_intensity - constraints for the indicator LED + in microamperes, + * has_external_strobe - determines whether the flash strobe source + can be switched to external, + +On remove the v4l2_flash_release function has to be called, which takes one +argument - struct v4l2_flash pointer returned previously by v4l2_flash_init. +This function can be safely called with NULL or error pointer argument. + +Please refer to drivers/leds/leds-max77693.c for an exemplary usage of the +v4l2 flash wrapper. + +Once the V4L2 sub-device is registered by the driver which created the Media +controller device, the sub-device node acts just as a node of a native V4L2 +flash API device would. The calls are simply routed to the LED flash API. + +Opening the V4L2 flash sub-device makes the LED subsystem sysfs interface +unavailable. The interface is re-enabled after the V4L2 flash sub-device +is closed. |