[systemd-devel] [PATCH] backlight: let the administrator override clamping

Topi Miettinen toiwoton at gmail.com
Sat Jan 17 05:07:27 PST 2015

On 01/17/15 12:48, David Herrmann wrote:
> Hi
> On Sat, Jan 17, 2015 at 1:41 PM, Topi Miettinen <toiwoton at gmail.com> wrote:
>> On 01/17/15 12:34, David Herrmann wrote:
>>> No, we still need clamping! In case your hardware has 256 brightness
>>> levels, we really don't want a brightness of 1 as it would still be
>>> far too dark.
>> How could you know that? The display can be too bright for the poor user
>> even at 4%.
> If the brightness scale is linear, I don't see how 5% can be "too
> bright". We write defaults that shall work for everyone.

You are lucky not to have my eyes or hardware. It does not work for me.

> You can
> easily disable our helpers and employ your own. But we cant provide
> configuration hooks for each and every obscure use-case. We want
> people to disable the defaults and write their own, if they don't like
> the defaults.

I understand that you don't want additional knobs to be maintained, but
in this case it's not possible to override the clamping logic other way.
I can of course disable the backlight entirely but then I would miss the
save/restore functionality.

How about splitting the logic into two? The other helper would only
perform save and restore and the other would decide if the values are
reasonable for the current kernel version and hardware of the day?

> In your case, it's an outright bug, though. And we want bugs to be
> fixed, instead of workarounds if developers are too lazy to fix their
> stuff.

I fully agree, for me the bug is in clamping logic and the fact that it
can't be overridden or separated from loading.

> Thanks
> David

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