[Server-devel] turn off backlight on XS-on-XO1

[rihoward1 at gmail.com]

This is documented at http://wiki.laptop.org/go/DCON_Linux_Driver


rihoward1 at gmail.com





On Mar 2, 2010, at 8:42 PM, James Cameron wrote:

> On Tue, Mar 02, 2010 at 09:00:50PM -0600, Anna wrote:
>> I'd appreciate a command to blank the screen.
> 
> Your subject line mentions the backlight, and blanking the screen is
> potentially a different task.
> 
> I've tested an XO-1 with build 802b1.
> 
> If you mean the backlight, you can manually control this from a shell
> command or program like this:
> 
> echo 0 > /sys/class/backlight/dcon-bl/brightness
> 
> or
> 
> echo 0 > /sys/devices/platform/dcon/backlight/dcon-bl/brightness
> 
> Change the 0 to 15 for full brightness.  With the backlight off, the
> screen image should still be visible.
> 
> You can manually turn off the screen and hide the screen image with this
> shell command:
> 
> echo 1 > /sys/devices/platform/dcon/sleep
> 
> But it doesn't turn back on automatically.  You can appear to lose
> control this way; you can restore it to normal with this:
> 
> echo 0 > /sys/devices/platform/dcon/sleep
> 
> The text console does idle blank after a while, though without turning
> off the backlight.
> 
> It is possible to initiate screen blanking manually using code that
> calls ioctl with TIOCLINUX and TIOCL_BLANKSCREEN but like the idle
> console blanking it leaves square brackets on screen.  The other three
> modes of VESA blanking that the kernel can do (TIOCL_SETVESABLANK) don't
> fare any better than the default.  Two of the modes do the bit rot melt down
> effect on the display.
> 
> It is also possible to manipulate the blanking timers using escape
> sequences sent to /dev/tty1 ... but again, we haven't integrated the
> VESA blanking feature of the kernel with our DCON and backlight.
> 
> -- 
> James Cameron
> http://quozl.linux.org.au/
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