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    SubjectRe: [PATCH 2/3] leds-clevo-mail: hw accelerated LED blink extension
    On Sun, 2007-10-21 at 14:54 +0200, Németh Márton wrote:
    > From: Márton Németh <>
    > Extends the leds subsystem with a blink_set() callback function which can
    > be optionally implemented by a LED driver. If implemented, the driver can use
    > the hardware acceleration for blinking a LED.
    > Signed-off-by: Márton Németh <>
    > ---
    > diff -uprN linux-2.6.23.orig/Documentation/leds-class.txt linux-2.6.23/Documentation/leds-class.txt
    > --- linux-2.6.23.orig/Documentation/leds-class.txt 2007-10-09 22:31:38.000000000 +0200
    > +++ linux-2.6.23/Documentation/leds-class.txt 2007-10-21 10:45:35.000000000 +0200
    > @@ -47,6 +49,19 @@ overhead, I suggest these become part of
    > above leaves scope for further attributes should they be needed.
    > +
    > +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 implemeted, the
    > +ledtrig-timer tries to use it. The blink_set() function should return
    > +0 if the blink setting is supported, or -EINVAL otherwise, which means
    > +that the LED will be turned on and off from software by the leds
    > +subsystem.

    Hardware acceleration of the timer triggers is great to see and worst
    case I'll happily apply this patch to the LED tree, thanks.

    Before I do, I did wonder if we should enhance the meaning of the
    set_blink function a bit. If set_blink is called with delay_on = 0,
    delay_off = 0 it could mean "blink with some user friendly value,
    hardware assisted". The use for this would be a more generic blink
    trigger where you wouldn't need to know about magically hardware
    assisted values for blinking, it would simply make an LED blink in a
    hardware assisted way.

    We also need to document that the brightness_set overrides any blinking
    which may or may not be active (which is implied in your driver).



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