Radeon Backlight

radeontool is a hack I created to save some battery on my Dell Latitude C610 with an ATI Radeon Mobility graphics chip. Radeontool can turn off and on the backlight and external video output. Radeontool requires lspci.

lightwatch.pl is a long-running perl script which toggles the backlight when the xscreensaver activates. I configured my sessions to run it whenever I log in (Preferences->MorePreferences->Sessions). You need to make it suid root and install perl-suidperl. Bill "Vuud" Chmura created a second version which is aware of the AC power status.

When I start XFree86 4.2 it activates both my HD15 CRT output and the LCD. With this tool I can disable each of them. For reference my XF86Config-4 is available.

I have been unable to activate the TV out. It would be easier if I had the radeon documentation. Please feel free to send it to software (a) this hostname.

Thanks for patches from Deepak Chawla, Erno Kuusela, Rolf Offermanns, Soos Peter, and Matthew Strait (delayed blanking), Darin Nelson (radeon 9100 IGP) for radeontool patches.

Soos Peter wrote a very cool Linux kernel module radeonlcd which toggles the backlight when Linux blanks the framebuffer (i.e. console not XWindows).

Takanori Watanabe ported it to FreeBSD.

Apparently, the latest XFree86 in CVS (i.e. after 4.3.0) has a fix to control the backlight.

Dell Latitude C610

I learned that the backlight can be turned off on my Dell Inspiron C610 by Fn+D. It goes back on when I hit a key. Also Fn+Z fixes the fan and temperature sensor after software suspend! Why suspend doesn't do that automatically I will not understand.

I really like my Latitude C610 and its 1400x1050 screen, but please stop with the stupid screen resolution acronyms. Screens should be sold by megapixel just like cameras: 1.47 megapixel.

I have had troubles with it overheating. Apparently, the top PCMCIA slot is safer than the bottom one. It burned my Cisco WiFi card, and my Xircom Ethernet crashes the kernel when it gets too hot.

Once one of the screws fell out of the bottom. Dell sent free replacements, although it took us several tries to determine the right ones. Now, I tighten them every month and have had no more trouble.

I shall not buy another computer that pays the Microsoft tax, so this may be my last Dell laptop.

	Name	Last modified	Size	Description
	Parent Directory		-
	CHANGES.txt	12-Feb-2004 15:41	437
	XF86Config-4.gz	01-Jul-2002 22:38	1.8K
	delayed_blanking.txt	28-Jul-2004 09:20	1.0K
	lightwatch.pl	26-Oct-2003 10:02	814
	lightwatch2.pl	07-Jan-2004 23:37	3.3K
	radeon9100.txt	28-Jul-2004 09:16	599
	radeonlcd-2004-02-04.tar.gz	04-Feb-2004 12:09	24K
	radeontool-1.0.tar.gz	01-Jul-2002 22:48	19K
	radeontool-1.2.tar.gz	26-Oct-2003 10:01	20K
	radeontool-1.3.tar.gz	03-Feb-2004 22:24	20K
	radeontool-1.4.tar.gz	04-Feb-2004 11:11	20K
	radeontool-1.5-1.i386.rpm	03-Mar-2004 21:25	7.8K
	radeontool-1.5.tar.gz	12-Feb-2004 15:41	20K
	radeontool.spec	03-Mar-2004 21:34	920
	radeontoolport.tar.gz	18-Aug-2005 10:41	2.0K
	vga_codes.txt	11-Feb-2004 17:13	560