Re: [PATCH] backlight: pm8941-wled: Add default-brightness property

On Thu 30 Jul 08:26 PDT 2015, Rob Herring wrote:

On Wed, Jul 29, 2015 at 6:51 PM, Bjorn Andersson
[off-list ref] wrote:

quoted

On Fri 24 Jul 08:29 PDT 2015, Rob Herring wrote:

[..]

quoted

As we're trying to specify a default brightness within the range [0,
max_brightness) the latter doesn't make much sense.

Therefor my suggestion is that we make the "default-brightness" the
common property and we define it as a percentage of [0,max_brightness).

Okay.

I wonder if we should have units such as
"default-brightness-percentage" or "default-brightness-%" so it is
clear. Otherwise, we might have some people doing a range of [0,max].
The former is a bit long and the latter is a bit unusual.

I discussed this further with my colleague and gave it some though over
the night;

If the boot loader sets the brightness, it would need to convert this to
a percentage just to have the kernel convert it back - with a expected
lack of precision (especially w/ non-linear brightness ranges or odd
step-sizes).

In the case where it's manually tweaked by the developer he/she would
most likely modify the brightness through sysfs until a reasonable value
is found; and we have that extra step again of converting this to a
percentage.


Therefor I think it's better to just specify this in "units of
brightness" - which would be a unit-less property.

Regards,
Bjorn