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    SubjectRe: [PATCH 0/3] Generic sysfs support for ACPI ALS and other ALS devices
    > > > No,
    > > > For a ALS policy, user space should set a brightness level as the base
    > > > point, i.e. the backlight when display adjustment is 100.
    > > > and then uses the adjustment values gotten from this mappings to
    > > > calculate the actual brightness level the display should be put in.
    > >
    > > Ok, so just make the code return only the "adjustement" -- userspace
    > > does not really need to know "illuminance" and you can do the mapping
    > > in the kernel AFAICT.
    > >
    >
    > ALS exports
    > 1. the current ambient light illuminance
    > 2. the mappings
    >
    > Backlight device exports
    > 1. the brightness levels.
    >
    > User space needs to:
    > 1. set a brightness level as the base point
    > 2. read the current ambient light illuminance from ALS device
    > 3. read the ambient light illuminance to display adjustment mappings
    > 4. calculate a proper brightness level we should set.
    >
    > For example, if we set brightness 6 as the default brightness, i.e. the
    > brightness level when ambient light illuminance is 300.
    > Now we walk outdoors, and the current illuminance is 1000,
    > then we should set the new_brightness_level to (6 * 150%)

    Yes, so just export

    ALS exports
    1. the current ambient light illuminance
    2. the current mapped ambient light illuminance

    Backlight device exports
    1. the brightness levels.

    User space needs to:
    1. set a brightness level as the base point
    2. read the current mapped ambient light illuminance from ALS device
    3. calculate a proper brightness level we should set.

    You get

    a) nicer interface
    b) simpler userland
    Pavel

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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