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-rw-r--r--Documentation/leds-class.txt21
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
60 60
61Some LEDs can be programmed to blink without any CPU interaction. To 61Some LEDs can be programmed to blink without any CPU interaction. To
62support this feature, a LED driver can optionally implement the 62support this feature, a LED driver can optionally implement the
63blink_set() function (see <linux/leds.h>). If implemented, triggers can 63blink_set() function (see <linux/leds.h>). To set an LED to blinking,
64attempt to use it before falling back to software timers. The blink_set() 64however, it is better to use use the API function led_blink_set(),
65function should return 0 if the blink setting is supported, or -EINVAL 65as it will check and implement software fallback if necessary.
66otherwise, which means that LED blinking will be handled by software. 66
67 67To turn off blinking again, use the API function led_brightness_set()
68The blink_set() function should choose a user friendly blinking 68as that will not just set the LED brightness but also stop any software
69value if it is called with *delay_on==0 && *delay_off==0 parameters. In 69timers that may have been required for blinking.
70this case the driver should give back the chosen value through delay_on 70
71and delay_off parameters to the leds subsystem. 71The blink_set() function should choose a user friendly blinking value
72if it is called with *delay_on==0 && *delay_off==0 parameters. In this
73case the driver should give back the chosen value through delay_on and
74delay_off parameters to the leds subsystem.
72 75
73Setting the brightness to zero with brightness_set() callback function 76Setting the brightness to zero with brightness_set() callback function
74should completely turn off the LED and cancel the previously programmed 77should completely turn off the LED and cancel the previously programmed