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Diffstat (limited to 'Documentation/leds-class.txt')
| -rw-r--r-- | Documentation/leds-class.txt | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/Documentation/leds-class.txt b/Documentation/leds-class.txt index 8fd5ca2ae32d..58b266bd1846 100644 --- a/Documentation/leds-class.txt +++ b/Documentation/leds-class.txt @@ -60,15 +60,18 @@ Hardware accelerated blink of LEDs Some LEDs can be programmed to blink without any CPU interaction. To support this feature, a LED driver can optionally implement the -blink_set() function (see <linux/leds.h>). If implemented, triggers can -attempt to use it before falling back to software timers. The blink_set() -function should return 0 if the blink setting is supported, or -EINVAL -otherwise, which means that LED blinking will be handled by software. - -The blink_set() function should choose a user friendly blinking -value if it is called with *delay_on==0 && *delay_off==0 parameters. In -this case the driver should give back the chosen value through delay_on -and delay_off parameters to the leds subsystem. +blink_set() function (see <linux/leds.h>). To set an LED to blinking, +however, it is better to use use the API function led_blink_set(), +as it will check and implement software fallback if necessary. + +To turn off blinking again, use the API function led_brightness_set() +as that will not just set the LED brightness but also stop any software +timers that may have been required for blinking. + +The blink_set() function should choose a user friendly blinking value +if it is called with *delay_on==0 && *delay_off==0 parameters. In this +case the driver should give back the chosen value through delay_on and +delay_off parameters to the leds subsystem. Setting the brightness to zero with brightness_set() callback function should completely turn off the LED and cancel the previously programmed |