Re: best way to handle LEDs

From: Richard Purdie (rpurdie_at_rpsys.net)
Date: 11/02/05

  • Next message: Dipankar Sarma: "bad page state under possibly oom situation" 
    To: Pavel Machek <pavel@suse.cz>
Date:	Wed, 02 Nov 2005 14:38:41 +0000

    On Wed, 2005-11-02 at 14:56 +0100, Pavel Machek wrote:
    > > Led triggers would be kernel sources of led on/off events. Some
    > > examples:
    > >
    > > 2Hz Heartbeat - useful for debugging (and/or Generic Timer)
    > > CPU Load indicator
    > > Charging indicator
    > > HDD activity (useful for microdrive on handheld)
    > > Network activity
    > > no doubt many more
    > >
    > > led triggers would be connected to leds via sysfs. Each trigger would
    > > probably have a number you could echo into an led's trigger attribute.
    > > Sensible default mappings could be had by assigning a default trigger to
    > > a device by name in the platform code that declares the led.
    >
    > Perhaps I'd keep it simple and leave it at
    >
    > * do hardcoded kernel action for this led
    >
    > or
    >
    > * do whatever userspace tells you.
    >
    > That way you will not be able to remap charger LED onto hard disk
    > indicator, but we can support that on ibm-acpi too. (Where hw controls
    > LEDs like "sleep", but lets you control them. You can't remap,
    > though).

    Then the arguments start about which function should be hardcoded to
    which leds and why can't userspace access these triggers?

    I'd prefer a totally flexible system and it doesn't really add much
    complexity once you have a trigger framework which we're going to need
    to handle mutiple led trigger sources sanely anyway.

    Richard

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