On Sat, 2009-12-19 at 10:55 -0800, Samuel Löf wrote: > Hi everyone, I have an idea for longer battery life in laptops. > I have a laptop with a big 17" widescreen, the screen uses 1680X1050 I > guess that the screen consume a large amount of the battery power. > What if one could lower the resulution without filling the whole > screen? For exemple 1280X800 with 125 pixel black border up and down, > and 200 pixel black border right and left. > > If I'm right the screen has orignally 1764000 (1680x1050) active > pixels and with the lower resolution 1024000 (1280x800) that is 740000 > less active pixels and probaly result in longer battery life. This is > probaly not a setting one would like to use all the time but I think > it would be a good "emergency mode" > > I have no idea if this is possible, is it? Is it a good idea?
There's a number of things that draw power here. One is the scanout engine. This will use power proportional to the size of the screen in pixels. A smaller real framebuffer will use less power. This means that merely faking a smaller framebuffer by drawing to only a subset of the screen will not reduce power consumption. Another is the display itself. Depending on the fabrication process of the LCD, different color states will have different power requirements. Typical LCDs are such that white is the least-power color, since you have to twist the crystals to block the (white) backlight from shining through, and twisting requires applying a voltage. So if you do border the screen, you'd want to set the border color to whatever the lowest-power border color is for your display. If you can't set a border color, you could try scaling the display up to fit the screen, but now you're in a tradeoff. The scanout engine will use less memory bandwidth (and thus less power), but will also have to turn on the scaler, which requires more power. Probably not a win, plus it'll look ugly. But really, the biggest power consumer by far is the backlight. Turn the backlight down. - ajax
signature.asc
Description: This is a digitally signed message part
_______________________________________________ xorg-devel mailing list [email protected] http://lists.x.org/mailman/listinfo/xorg-devel
