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Subject: Backlight fading - FS#6800

Backlight fading - FS#6800

From: Thomas Martitz <>
Date: Thu, 20 Nov 2008 19:36:23 +0100

Hi guys,

I'd like to talk about FS#6800.

It adds software controlled backlight fading for targets which don't
have backlight fading built-in into their hardware. It works simply by
incrementing and decrementing the backlight brightness in a given
intervall, using the backlight thread. This algorithm has one drawback:
It's dependent on the current brightness, and it won't fade when the
current brightness is set to the lowest level.

Other targets (existing and future ones) can be easily adapted if they
don't feature hardware fading, as long as they offer backlight
brightness. I already implemented it for e200, c200 and h300 (Gigabeat S
will get hardware fading, so this patch doesn't apply anymore). Future
targets would be at least Sansa e200v2 and Sansa Fuze, probably c200v2 too.

It can be configured, by the means you can enable and disable both
fading in and out sperately. I reuse existing strings from the lang
files for the settings and code of the settings for the pwm fading targets.

Any opinions on this patch? I surely like to have it committed. I'm open
to suggestions (you could possibly name targets which I've forgotten to

My pros on this patch:
1) keeps Rockbox consistent over targets (as in Rockbox generally
features backlight fading)
2) backlight fading is a nice effect. I, for one, can even use Rockbox
more relaxed, since a smooth backlight on procedure isn't as "epileptic
sezure" risking (not that I have epilepsy) as a instant on version, that
goes together with the point 4.
3) especially nice if the OF doesn't feature that, and thus one aspect
more in which Rockbox beats that OF. I remember backlight fading on the
iPod Nano is appreciated especially since the Apple OS doesn't offer it.
4) as a side effect (at least for e200) it gets rid of the noticeable
lcd_enable procedure when enabling the backlight. The e200's display
shortly "flashes", since due to lcd_enable the screen is cleared to all
white and this all white appears for a split second after the backlight
is turned on. This does not happen with the backlight fading enabled.
5) If, for any reason, you don't like the fading, you can turn it off as
you like. Like on targets which already feature that.

I'm sure the reason against it would be the same as always:
1) binsize
2) feature bloat
3) settings bloat

I think the pros out-weight the cons, especially since the last two cons
don't really apply as certain targets already offer it.

Kind regards, kugel
Received on 2008-11-20

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