Re: [PATCH] [Fwd: Console locking and blanking]

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2005-08-16 at 23:44 -0400, Steven Rostedt wrote:
> On Wed, 2005-08-17 at 13:29 +1000, Benjamin Herrenschmidt wrote:
> > On Wed, 2005-08-17 at 11:41 +1000, Benjamin Herrenschmidt wrote:
> > 
> > > (I'm blind and I use a braille display. I use those functions to blank 
> > > my laptop's screen so people don't read it, and hopefully to conserve 
> > > power.)
> 
> At the OLS I learned that the backlight of a laptop (when the screen is
> black, but still glows) actually spends more wattage than when the
> screen is lit.  So, unless you actually turn the laptop display off,
> switching it to black will actually burn the battery quicker.

Actually, it's not the backlight. The backlight definitely eats less
power when off. The panel itself, however, at least some of them afaik,
will use a bit more power for opaque pixels than for transparent pixels.

Ben.


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