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    SubjectRe: [PATCH 0/3] Generic sysfs support for ACPI ALS and other ALS devices
    On Wed 2009-08-05 09:02:50, Zhang Rui wrote:
    > On Tue, 2009-08-04 at 21:21 +0800, Pavel Machek wrote:
    > > On Mon 2009-08-03 17:10:57, Zhang Rui wrote:
    > > > Hi, all,
    > > >
    > > > This is the patch set I made to introduce ACPI ALS device driver
    > > > and a generic sysfs I/F for all the ALS devices, like ACPI ALS,
    > > > platform ALS, etc.
    > > >
    > > > Patch 01 introduces the ACPI ALS device driver.
    > > >
    > > > Patch 02 introduces ALS sysfs class.
    > > > Two sysfs I/F are created for each ALS device.
    > > > /sys/class/als/alsX/illuminance:
    > > > the amount of light incident upon a specified surface area.
    > > > /sys/class/als/alsX/mappings:
    > > > ambient light illuminance to display luminance mappings
    > > > that can be used by an OS to calibrate its ambient light policy
    > > > this is what I got on a test box:
    > > > cat /sys/class/als/als0/mappings
    > > > ???Illuminance Adjustment
    > > > 0 70
    > > > 10 73
    > > > 80 85
    > > > 300 100
    > > > 1000 150
    > >
    > > There's one value per file for sysfs... You should definitely have the
    > > header.
    > >
    > > Is there chance to already return adjusted values, avoiding this
    > > uglyness?
    >
    > 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.
    Pavel

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


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