Re: [PATCH 0/3] Generic sysfs support for ACPI ALS and other ALS devices

Pavel Machek
2009-08-06T07:14:02Z

> > > 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

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