Re: [Mactel-linux-users] Backlight control on Macbook Pro

[gimli <gi...@da...>]

Great work.

Nicolas Boichat wrote:
> Hi,
> 
> I just got initial support for LCD backlight control (source code
> attached), it helps saving battery, and your eyes .-)
> 
> Compile it with:
> gcc backlight.c -o backlight
> 
> and run it, as root:
> # ./backlight (get current value)
> Current value : 14
> # ./backlight 15 (set value (15 is maximum, 0 minimum))
> 
> Maybe it should be integrated in the kernel, but I don't know where
> (ACPI??). Does anyone know if 0xB2 and 0xB3 are standard registers?
> 
> Tested with Bootcamp, I don't know whether it also works with the legacy
> EFI.
> 
> Best regards,
> 
> Nicolas
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
> /*
>  * Apple Macbook Pro LCD backlight control
>  *
>  * Copyright (C) 2006 Nicolas Boichat <ni...@bo...>
>  *
>  * This program is free software; you can redistribute it and/or modify
>  * it under the terms of the GNU General Public License as published by
>  * the Free Software Foundation; either version 2 of the License, or
>  * (at your option) any later version.
>  *
>  * This program is distributed in the hope that it will be useful,
>  * but WITHOUT ANY WARRANTY; without even the implied warranty of
>  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>  * GNU General Public License for more details.
>  *
>  * You should have received a copy of the GNU General Public License
>  * along with this program; if not, write to the Free Software
>  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>  *
>  */
> 
> #include <stdio.h>
> #include <sys/io.h>
> #include <stdlib.h>
> 
> int main(int argc, char** argv) {
> 	int value = -1;
> 
> 	if (argc > 2) {
> 		printf("Usage:\n");
> 		printf("%s : read current value\n", argv[0]);
> 		printf("%s value : write value [0-15]\n", argv[0]);
> 	}
> 	
> 	if (argc == 2) {
> 		value = atoi(argv[1]);
> 		if ((value < 0) || (value > 15)) {
> 			printf("Invalid value (should be between 0 and 15).\n");
> 			exit(0);
> 		}
> 	}
> 	
> 	if (ioperm(0xB2, 0xB3, 1) < 0) {
> 		perror("ioperm failed (you should be root).");
> 		exit(1);
> 	}
> 
> 	if (value < 0) {
> 		outb(0x03, 0xB3);
> 		outb(0xBF, 0xB2);
> 		char t = inb(0xB3) >> 4;
> 		printf("Current value : %d\n", t);
> 	}
> 	else {
> 		outb(0x04 | (value << 4), 0xB3);
> 		outb(0xBF, 0xB2);
> 	}
> 
> 	return 0;
> }