On Thu 2015-02-05 09:42:53, Jacek Anaszewski wrote:
> The documentation being added contains overall description of the
> LED Flash Class and the related sysfs attributes.
>
> Signed-off-by: Jacek Anaszewski <[email protected]>
> Acked-by: Kyungmin Park <[email protected]>
> Cc: Bryan Wu <[email protected]>
> Cc: Richard Purdie <[email protected]>
> ---
> Documentation/leds/leds-class-flash.txt | 63
> +++++++++++++++++++++++++++++++
> 1 file changed, 63 insertions(+)
> create mode 100644 Documentation/leds/leds-class-flash.txt
>
> diff --git a/Documentation/leds/leds-class-flash.txt
> b/Documentation/leds/leds-class-flash.txt
> new file mode 100644
> index 0000000..16c6187
> --- /dev/null
> +++ b/Documentation/leds/leds-class-flash.txt
> @@ -0,0 +1,63 @@
> +
> +Flash LED handling under Linux
> +==============================
> +
> +Some LED devices support two modes - torch and flash. In the LED subsystem
> +those modes are supported by LED class (see
> Documentation/leds/leds-class.txt)
> +and LED Flash class respectively. The torch mode related features are enabled
> +by default and the flash ones only if a driver declares it by setting
> +LED_DEV_CAP_FLASH flag.
> +
> +In order to enable support for flash LEDs CONFIG_LEDS_CLASS_FLASH symbol
> +must be defined in the kernel config. A flash LED driver must register
> +in the LED subsystem with led_classdev_flash_register function to gain flash
> +related capabilities.
> +
> +There are flash LED devices which can control more than one LED and allow for
> +strobing the sub-LEDs synchronously. A LED will be strobed synchronously with
> +the one whose identifier is written to the flash_sync_strobe sysfs attribute.
> +The list of available sub-LED identifiers can be read from the
> available_sync_leds
> +sysfs attribute. In order to enable the related settings the driver must set
> +LED_DEV_CAP_SYNC_STROBE flag.
> +
> +Following sysfs attributes are exposed for controlling flash LED devices:
> +
> + - flash_brightness - flash LED brightness in microamperes (RW)
> + - max_flash_brightness - maximum available flash LED brightness (RO)
in microamperes
> + - flash_timeout - flash strobe duration in microseconds (RW)
> + - max_flash_timeout - maximum available flash strobe duration
> (RO)
in microseconds
> + - flash_strobe - flash strobe state (RW)
This is integer..?
> + - available_sync_leds - list of sub-LEDs available for flash strobe
> + synchronization (RO)
"space separated"?
So this will say something like "0 3 5"
> + - flash_sync_strobe - identifier of the sub-LED to synchronize the flash
> + strobe with; 0 stands for no synchronization (RW)
...and it means that I can put 0, 3 or 5 into this file?
> + - flash_fault - list of flash faults that may have occurred:
"space separated"?
> + * led-over-voltage - flash controller voltage to the flash LED
> + has exceededthe limit specific to the flash controller
> + * flash-timeout-exceeded - the flash strobe was still on when
> + the timeout set by the user has expired; not all flash
> + controllers may set this in all such conditions
> + * controller-over-temperature - the flash controller has
> + overheated
> + * controller-short-circuit - the short circuit protection
> + of the flash controller has been triggered
> + * led-power-supply-over-current - current in the LED power
> + supply has exceeded the limit specific to the flash
> + controller
> + * indicator-led-fault - the flash controller has detected
> + a short or open circuit condition on the indicator LED
> + * led-under-voltage - flash controller voltage to the flash
> + LED has been below the minimum limit specific to
> + the flash
> + * controller-under-voltage - the input voltage of the flash
> + controller is below the limit under which strobing the
> + flash at full current will not be possible;
> + the condition persists until this flag is no longer set
> + * led-over-temperature - the temperature of the LED has exceeded
> + its allowed upper limit
> +
> + Flash faults should be read in the strobe_set callback, right
> + after the instruction initiating the strobe. If a flash LED
Ok, so this is part sysfs documentation, part kernel class
documentation... it is a bit confusing.
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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