I said nothing about changing "led_current" beyond the fact that I thought he might be thinking of that (because at the time I had only seen the led_current thing have any effect). I keep my keyboard led_current values at the stock 50, and am just fine with it, nor have I advised anyone to change it. My boot-shell /sbin/preinit script touches only the brightness value, not the led_current value.

P.S. I appreciate the informativeness, but many people don't read things fully or properly, and I'm sure there's readers who would've combined a skimming of my post and a skimming of your post to suppose I was doing something damaging with my press-any-key-for-shell at boot script.

(Do you know if NITDroid is using higher led_current values? Or does NITDroid actually do it by brightness? Because there are posts on this forum suggesting using led_current to force keyboard to be as bright as it is when NITDroid is booted. I haven't heard anyone yet say their leds are malfunctioning, but like overclocking, it's probably one of those matter-of-time things. Honestly, this is what happens when software/hardware makers don't give users proper control over aspects of hardware - since during normal after-MCE-kicks-in operation led_current is the only way to make the brightness higher for a minimally command-line capable person, that's what people will naturally turn to.)

Hmm. So that's where that came from. Near as I can tell it just always makes the brightness value equal to itself, unless set to -1, which it always is by default on my device. Do you know what Titan's reasoning was for including/implementing it?

So in practice, we're at what I said earlier "brightness files control kbd backlight in early boot, and something else takes over later". (But now I know it's mce that does the controlling from there, and that the brightness files really do still control the keyboard, they're just zealously overriden; so thank you. MCE is closed source, right?)

Indeed it does. Very informative bit of advice (since the same logic probably helps figure out issues in plenty of other scenarios.