| Message ID | 1433754145-12765-2-git-send-email-j.anaszewski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jun 8, 2015 at 2:02 AM, Jacek Anaszewski <j.anaszewski@samsung.com> wrote: > This patch extends LED Flash class documention by > the description of interactions with v4l2-flash sub-device. > Merged into my -devel branch and it won't be merged into 4.2.0 merge window but wait for one more cycle, since now it's quite late in 4.1.0 cycle. Thanks, -Bryan > Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> > Acked-by: Kyungmin Park <kyungmin.park@samsung.com> > Cc: Richard Purdie <rpurdie@rpsys.net> > --- > Documentation/leds/leds-class-flash.txt | 51 +++++++++++++++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt > index 19bb673..8da3c6f 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. > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt index 19bb673..8da3c6f 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.