Merge commit 'v2.6.36' into kbuild/misc

Update to be able to fix a recent change to scripts/basic/docproc.c
(commit eda603f).

6 files changed, 251 insertions, 248 deletions

diff --git a/Documentation/laptops/00-INDEX b/Documentation/laptops/00-INDEX
index ee5692b26dd4..fa688538e757 100644
--- a/Documentation/laptops/00-INDEX
+++ b/Documentation/laptops/00-INDEX
@@ -2,6 +2,12 @@
 	- This file
 acer-wmi.txt
 	- information on the Acer Laptop WMI Extras driver.
+asus-laptop.txt
+	- information on the Asus Laptop Extras driver.
+disk-shock-protection.txt
+	- information on hard disk shock protection.
+dslm.c
+	- Simple Disk Sleep Monitor program
 laptop-mode.txt
 	- how to conserve battery power using laptop-mode.
 sony-laptop.txt
diff --git a/Documentation/laptops/Makefile b/Documentation/laptops/Makefile
new file mode 100644
index 000000000000..5cb144af3c09
--- /dev/null
+++ b/Documentation/laptops/Makefile
@@ -0,0 +1,8 @@
+# kbuild trick to avoid linker error. Can be omitted if a module is built.
+obj- := dummy.o
+
+# List of programs to build
+hostprogs-y := dslm
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
diff --git a/Documentation/laptops/acer-wmi.txt b/Documentation/laptops/acer-wmi.txt
index 0768fcc3ba3e..4beafa663dd6 100644
--- a/Documentation/laptops/acer-wmi.txt
+++ b/Documentation/laptops/acer-wmi.txt
@@ -173,7 +173,7 @@ Credits
 *******
 
 Olaf Tauber, who did the real hard work when he developed acerhk
-http://www.informatik.hu-berlin.de/~tauber/acerhk
+http://www.cakey.de/acerhk/
 All the authors of laptop ACPI modules in the kernel, whose work
 was an inspiration in the early days of acer_acpi
 Mathieu Segaud, who solved the problem with having to modprobe the driver
diff --git a/Documentation/laptops/dslm.c b/Documentation/laptops/dslm.c
new file mode 100644
index 000000000000..72ff290c5fc6
--- /dev/null
+++ b/Documentation/laptops/dslm.c
@@ -0,0 +1,166 @@
+/*
+ * dslm.c
+ * Simple Disk Sleep Monitor
+ *  by Bartek Kania
+ * Licenced under the GPL
+ */
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <time.h>
+#include <string.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <linux/hdreg.h>
+
+#ifdef DEBUG
+#define D(x) x
+#else
+#define D(x)
+#endif
+
+int endit = 0;
+
+/* Check if the disk is in powersave-mode
+ * Most of the code is stolen from hdparm.
+ * 1 = active, 0 = standby/sleep, -1 = unknown */
+static int check_powermode(int fd)
+{
+    unsigned char args[4] = {WIN_CHECKPOWERMODE1,0,0,0};
+    int state;
+
+    if (ioctl(fd, HDIO_DRIVE_CMD, &args)
+	&& (args[0] = WIN_CHECKPOWERMODE2) /* try again with 0x98 */
+	&& ioctl(fd, HDIO_DRIVE_CMD, &args)) {
+	if (errno != EIO || args[0] != 0 || args[1] != 0) {
+	    state = -1; /* "unknown"; */
+	} else
+	    state = 0; /* "sleeping"; */
+    } else {
+	state = (args[2] == 255) ? 1 : 0;
+    }
+    D(printf(" drive state is:  %d\n", state));
+
+    return state;
+}
+
+static char *state_name(int i)
+{
+    if (i == -1) return "unknown";
+    if (i == 0) return "sleeping";
+    if (i == 1) return "active";
+
+    return "internal error";
+}
+
+static char *myctime(time_t time)
+{
+    char *ts = ctime(&time);
+    ts[strlen(ts) - 1] = 0;
+
+    return ts;
+}
+
+static void measure(int fd)
+{
+    time_t start_time;
+    int last_state;
+    time_t last_time;
+    int curr_state;
+    time_t curr_time = 0;
+    time_t time_diff;
+    time_t active_time = 0;
+    time_t sleep_time = 0;
+    time_t unknown_time = 0;
+    time_t total_time = 0;
+    int changes = 0;
+    float tmp;
+
+    printf("Starting measurements\n");
+
+    last_state = check_powermode(fd);
+    start_time = last_time = time(0);
+    printf("  System is in state %s\n\n", state_name(last_state));
+
+    while(!endit) {
+	sleep(1);
+	curr_state = check_powermode(fd);
+
+	if (curr_state != last_state || endit) {
+	    changes++;
+	    curr_time = time(0);
+	    time_diff = curr_time - last_time;
+
+	    if (last_state == 1) active_time += time_diff;
+	    else if (last_state == 0) sleep_time += time_diff;
+	    else unknown_time += time_diff;
+
+	    last_state = curr_state;
+	    last_time = curr_time;
+
+	    printf("%s: State-change to %s\n", myctime(curr_time),
+		   state_name(curr_state));
+	}
+    }
+    changes--; /* Compensate for SIGINT */
+
+    total_time = time(0) - start_time;
+    printf("\nTotal running time:  %lus\n", curr_time - start_time);
+    printf(" State changed %d times\n", changes);
+
+    tmp = (float)sleep_time / (float)total_time * 100;
+    printf(" Time in sleep state:   %lus (%.2f%%)\n", sleep_time, tmp);
+    tmp = (float)active_time / (float)total_time * 100;
+    printf(" Time in active state:  %lus (%.2f%%)\n", active_time, tmp);
+    tmp = (float)unknown_time / (float)total_time * 100;
+    printf(" Time in unknown state: %lus (%.2f%%)\n", unknown_time, tmp);
+}
+
+static void ender(int s)
+{
+    endit = 1;
+}
+
+static void usage(void)
+{
+    puts("usage: dslm [-w <time>] <disk>");
+    exit(0);
+}
+
+int main(int argc, char **argv)
+{
+    int fd;
+    char *disk = 0;
+    int settle_time = 60;
+
+    /* Parse the simple command-line */
+    if (argc == 2)
+	disk = argv[1];
+    else if (argc == 4) {
+	settle_time = atoi(argv[2]);
+	disk = argv[3];
+    } else
+	usage();
+
+    if (!(fd = open(disk, O_RDONLY|O_NONBLOCK))) {
+	printf("Can't open %s, because: %s\n", disk, strerror(errno));
+	exit(-1);
+    }
+
+    if (settle_time) {
+	printf("Waiting %d seconds for the system to settle down to "
+	       "'normal'\n", settle_time);
+	sleep(settle_time);
+    } else
+	puts("Not waiting for system to settle down");
+
+    signal(SIGINT, ender);
+
+    measure(fd);
+
+    close(fd);
+
+    return 0;
+}
diff --git a/Documentation/laptops/laptop-mode.txt b/Documentation/laptops/laptop-mode.txt
index eeedee11c8c2..0bf25eebce94 100644
--- a/Documentation/laptops/laptop-mode.txt
+++ b/Documentation/laptops/laptop-mode.txt
@@ -207,7 +207,7 @@ Tips & Tricks
 * Drew Scott Daniels observed: "I don't know why, but when I decrease the number
   of colours that my display uses it consumes less battery power. I've seen
   this on powerbooks too. I hope that this is a piece of information that
-  might be useful to the Laptop Mode patch or it's users."
+  might be useful to the Laptop Mode patch or its users."
 
 * In syslog.conf, you can prefix entries with a dash ``-'' to omit syncing the
   file after every logging. When you're using laptop-mode and your disk doesn't
@@ -779,172 +779,4 @@ Monitoring tool
 ---------------
 
 Bartek Kania submitted this, it can be used to measure how much time your disk
-spends spun up/down.
-
----------------------------dslm.c BEGIN-----------------------------------------
-/*
- * Simple Disk Sleep Monitor
- *  by Bartek Kania
- * Licenced under the GPL
- */
-#include <unistd.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <fcntl.h>
-#include <errno.h>
-#include <time.h>
-#include <string.h>
-#include <signal.h>
-#include <sys/ioctl.h>
-#include <linux/hdreg.h>
-
-#ifdef DEBUG
-#define D(x) x
-#else
-#define D(x)
-#endif
-
-int endit = 0;
-
-/* Check if the disk is in powersave-mode
- * Most of the code is stolen from hdparm.
- * 1 = active, 0 = standby/sleep, -1 = unknown */
-int check_powermode(int fd)
-{
-    unsigned char args[4] = {WIN_CHECKPOWERMODE1,0,0,0};
-    int state;
-
-    if (ioctl(fd, HDIO_DRIVE_CMD, &args)
-	&& (args[0] = WIN_CHECKPOWERMODE2) /* try again with 0x98 */
-	&& ioctl(fd, HDIO_DRIVE_CMD, &args)) {
-	if (errno != EIO || args[0] != 0 || args[1] != 0) {
-	    state = -1; /* "unknown"; */
-	} else
-	    state = 0; /* "sleeping"; */
-    } else {
-	state = (args[2] == 255) ? 1 : 0;
-    }
-    D(printf(" drive state is:  %d\n", state));
-
-    return state;
-}
-
-char *state_name(int i)
-{
-    if (i == -1) return "unknown";
-    if (i == 0) return "sleeping";
-    if (i == 1) return "active";
-
-    return "internal error";
-}
-
-char *myctime(time_t time)
-{
-    char *ts = ctime(&time);
-    ts[strlen(ts) - 1] = 0;
-
-    return ts;
-}
-
-void measure(int fd)
-{
-    time_t start_time;
-    int last_state;
-    time_t last_time;
-    int curr_state;
-    time_t curr_time = 0;
-    time_t time_diff;
-    time_t active_time = 0;
-    time_t sleep_time = 0;
-    time_t unknown_time = 0;
-    time_t total_time = 0;
-    int changes = 0;
-    float tmp;
-
-    printf("Starting measurements\n");
-
-    last_state = check_powermode(fd);
-    start_time = last_time = time(0);
-    printf("  System is in state %s\n\n", state_name(last_state));
-
-    while(!endit) {
-	sleep(1);
-	curr_state = check_powermode(fd);
-
-	if (curr_state != last_state || endit) {
-	    changes++;
-	    curr_time = time(0);
-	    time_diff = curr_time - last_time;
-
-	    if (last_state == 1) active_time += time_diff;
-	    else if (last_state == 0) sleep_time += time_diff;
-	    else unknown_time += time_diff;
-
-	    last_state = curr_state;
-	    last_time = curr_time;
-
-	    printf("%s: State-change to %s\n", myctime(curr_time),
-		   state_name(curr_state));
-	}
-    }
-    changes--; /* Compensate for SIGINT */
-
-    total_time = time(0) - start_time;
-    printf("\nTotal running time:  %lus\n", curr_time - start_time);
-    printf(" State changed %d times\n", changes);
-
-    tmp = (float)sleep_time / (float)total_time * 100;
-    printf(" Time in sleep state:   %lus (%.2f%%)\n", sleep_time, tmp);
-    tmp = (float)active_time / (float)total_time * 100;
-    printf(" Time in active state:  %lus (%.2f%%)\n", active_time, tmp);
-    tmp = (float)unknown_time / (float)total_time * 100;
-    printf(" Time in unknown state: %lus (%.2f%%)\n", unknown_time, tmp);
-}
-
-void ender(int s)
-{
-    endit = 1;
-}
-
-void usage()
-{
-    puts("usage: dslm [-w <time>] <disk>");
-    exit(0);
-}
-
-int main(int argc, char **argv)
-{
-    int fd;
-    char *disk = 0;
-    int settle_time = 60;
-
-    /* Parse the simple command-line */
-    if (argc == 2)
-	disk = argv[1];
-    else if (argc == 4) {
-	settle_time = atoi(argv[2]);
-	disk = argv[3];
-    } else
-	usage();
-
-    if (!(fd = open(disk, O_RDONLY|O_NONBLOCK))) {
-	printf("Can't open %s, because: %s\n", disk, strerror(errno));
-	exit(-1);
-    }
-
-    if (settle_time) {
-	printf("Waiting %d seconds for the system to settle down to "
-	       "'normal'\n", settle_time);
-	sleep(settle_time);
-    } else
-	puts("Not waiting for system to settle down");
-
-    signal(SIGINT, ender);
-
-    measure(fd);
-
-    close(fd);
-
-    return 0;
-}
----------------------------dslm.c END-------------------------------------------
+spends spun up/down.  See Documentation/laptops/dslm.c
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index 75afa1229fd7..1565eefd6fd5 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -292,13 +292,13 @@ sysfs notes:
 
 		Warning: when in NVRAM mode, the volume up/down/mute
 		keys are synthesized according to changes in the mixer,
-		so you have to use volume up or volume down to unmute,
-		as per the ThinkPad volume mixer user interface.  When
-		in ACPI event mode, volume up/down/mute are reported as
-		separate events, but this behaviour may be corrected in
-		future releases of this driver, in which case the
-		ThinkPad volume mixer user interface semantics will be
-		enforced.
+		which uses a single volume up or volume down hotkey
+		press to unmute, as per the ThinkPad volume mixer user
+		interface.  When in ACPI event mode, volume up/down/mute
+		events are reported by the firmware and can behave
+		differently (and that behaviour changes with firmware
+		version -- not just with firmware models -- as well as
+		OSI(Linux) state).
 
 	hotkey_poll_freq:
 		frequency in Hz for hot key polling. It must be between
@@ -309,7 +309,7 @@ sysfs notes:
 		will cause hot key presses that require NVRAM polling
 		to never be reported.
 
-		Setting hotkey_poll_freq too low will cause repeated
+		Setting hotkey_poll_freq too low may cause repeated
 		pressings of the same hot key to be misreported as a
 		single key press, or to not even be detected at all.
 		The recommended polling frequency is 10Hz.
@@ -397,6 +397,7 @@ ACPI	Scan
 event	code	Key		Notes
 
 0x1001	0x00	FN+F1		-
+
 0x1002	0x01	FN+F2		IBM: battery (rare)
 				Lenovo: Screen lock
 
@@ -404,7 +405,8 @@ event	code	Key		Notes
 				this hot key, even with hot keys
 				disabled or with Fn+F3 masked
 				off
-				IBM: screen lock
+				IBM: screen lock, often turns
+				off the ThinkLight as side-effect
 				Lenovo: battery
 
 0x1004	0x03	FN+F4		Sleep button (ACPI sleep button
@@ -433,7 +435,8 @@ event	code	Key		Notes
 				Do you feel lucky today?
 
 0x1008	0x07	FN+F8		IBM: toggle screen expand
-				Lenovo: configure UltraNav
+				Lenovo: configure UltraNav,
+				or toggle screen expand
 
 0x1009	0x08	FN+F9		-
 	..	..		..
@@ -444,7 +447,7 @@ event	code	Key		Notes
 				either through the ACPI event,
 				or through a hotkey event.
 				The firmware may refuse to
-				generate further FN+F4 key
+				generate further FN+F12 key
 				press events until a S3 or S4
 				ACPI sleep cycle is performed,
 				or some time passes.
@@ -512,15 +515,19 @@ events for switches:
 SW_RFKILL_ALL	T60 and later hardware rfkill rocker switch
 SW_TABLET_MODE	Tablet ThinkPads HKEY events 0x5009 and 0x500A
 
-Non hot-key ACPI HKEY event map:
+Non hotkey ACPI HKEY event map:
+-------------------------------
+
+Events that are not propagated by the driver, except for legacy
+compatibility purposes when hotkey_report_mode is set to 1:
+
 0x5001		Lid closed
 0x5002		Lid opened
 0x5009		Tablet swivel: switched to tablet mode
 0x500A		Tablet swivel: switched to normal mode
 0x7000		Radio Switch may have changed state
 
-The above events are not propagated by the driver, except for legacy
-compatibility purposes when hotkey_report_mode is set to 1.
+Events that are never propagated by the driver:
 
 0x2304		System is waking up from suspend to undock
 0x2305		System is waking up from suspend to eject bay
@@ -528,14 +535,39 @@ compatibility purposes when hotkey_report_mode is set to 1.
 0x2405		System is waking up from hibernation to eject bay
 0x5010		Brightness level changed/control event
 
-The above events are never propagated by the driver.
+Events that are propagated by the driver to userspace:
 
+0x2313		ALARM: System is waking up from suspend because
+		the battery is nearly empty
+0x2413		ALARM: System is waking up from hibernation because
+		the battery is nearly empty
 0x3003		Bay ejection (see 0x2x05) complete, can sleep again
+0x3006		Bay hotplug request (hint to power up SATA link when
+		the optical drive tray is ejected)
 0x4003		Undocked (see 0x2x04), can sleep again
 0x500B		Tablet pen inserted into its storage bay
 0x500C		Tablet pen removed from its storage bay
-
-The above events are propagated by the driver.
+0x6011		ALARM: battery is too hot
+0x6012		ALARM: battery is extremely hot
+0x6021		ALARM: a sensor is too hot
+0x6022		ALARM: a sensor is extremely hot
+0x6030		System thermal table changed
+
+Battery nearly empty alarms are a last resort attempt to get the
+operating system to hibernate or shutdown cleanly (0x2313), or shutdown
+cleanly (0x2413) before power is lost.  They must be acted upon, as the
+wake up caused by the firmware will have negated most safety nets...
+
+When any of the "too hot" alarms happen, according to Lenovo the user
+should suspend or hibernate the laptop (and in the case of battery
+alarms, unplug the AC adapter) to let it cool down.  These alarms do
+signal that something is wrong, they should never happen on normal
+operating conditions.
+
+The "extremely hot" alarms are emergencies.  According to Lenovo, the
+operating system is to force either an immediate suspend or hibernate
+cycle, or a system shutdown.  Obviously, something is very wrong if this
+happens.
 
 Compatibility notes:
 
@@ -650,6 +682,10 @@ LCD, CRT or DVI (if available). The following commands are available:
 	echo expand_toggle > /proc/acpi/ibm/video
 	echo video_switch > /proc/acpi/ibm/video
 
+NOTE: Access to this feature is restricted to processes owning the
+CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
+enough with some versions of X.org to crash it.
+
 Each video output device can be enabled or disabled individually.
 Reading /proc/acpi/ibm/video shows the status of each device.
 
@@ -924,70 +960,21 @@ Sysfs notes:
 	subsystem, and follow all of the hwmon guidelines at
 	Documentation/hwmon.
 
+EXPERIMENTAL: Embedded controller register dump
+-----------------------------------------------
 
-EXPERIMENTAL: Embedded controller register dump -- /proc/acpi/ibm/ecdump
-------------------------------------------------------------------------
-
-This feature is marked EXPERIMENTAL because the implementation
-directly accesses hardware registers and may not work as expected. USE
-WITH CAUTION! To use this feature, you need to supply the
-experimental=1 parameter when loading the module.
-
-This feature dumps the values of 256 embedded controller
-registers. Values which have changed since the last time the registers
-were dumped are marked with a star:
-
-[root@x40 ibm-acpi]# cat /proc/acpi/ibm/ecdump
-EC       +00 +01 +02 +03 +04 +05 +06 +07 +08 +09 +0a +0b +0c +0d +0e +0f
-EC 0x00:  a7  47  87  01  fe  96  00  08  01  00  cb  00  00  00  40  00
-EC 0x10:  00  00  ff  ff  f4  3c  87  09  01  ff  42  01  ff  ff  0d  00
-EC 0x20:  00  00  00  00  00  00  00  00  00  00  00  03  43  00  00  80
-EC 0x30:  01  07  1a  00  30  04  00  00 *85  00  00  10  00  50  00  00
-EC 0x40:  00  00  00  00  00  00  14  01  00  04  00  00  00  00  00  00
-EC 0x50:  00  c0  02  0d  00  01  01  02  02  03  03  03  03 *bc *02 *bc
-EC 0x60: *02 *bc *02  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0x70:  00  00  00  00  00  12  30  40 *24 *26 *2c *27 *20  80 *1f  80
-EC 0x80:  00  00  00  06 *37 *0e  03  00  00  00  0e  07  00  00  00  00
-EC 0x90:  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xa0: *ff  09  ff  09  ff  ff *64  00 *00 *00 *a2  41 *ff *ff *e0  00
-EC 0xb0:  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xc0:  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xd0:  03  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xe0:  00  00  00  00  00  00  00  00  11  20  49  04  24  06  55  03
-EC 0xf0:  31  55  48  54  35  38  57  57  08  2f  45  73  07  65  6c  1a
-
-This feature can be used to determine the register holding the fan
-speed on some models. To do that, do the following:
+This feature is not included in the thinkpad driver anymore.
+Instead the EC can be accessed through /sys/kernel/debug/ec with
+a userspace tool which can be found here:
+ftp://ftp.suse.com/pub/people/trenn/sources/ec
 
+Use it to determine the register holding the fan
+speed on some models. To do that, do the following:
 	- make sure the battery is fully charged
 	- make sure the fan is running
-	- run 'cat /proc/acpi/ibm/ecdump' several times, once per second or so
-
-The first step makes sure various charging-related values don't
-vary. The second ensures that the fan-related values do vary, since
-the fan speed fluctuates a bit. The third will (hopefully) mark the
-fan register with a star:
-
-[root@x40 ibm-acpi]# cat /proc/acpi/ibm/ecdump
-EC       +00 +01 +02 +03 +04 +05 +06 +07 +08 +09 +0a +0b +0c +0d +0e +0f
-EC 0x00:  a7  47  87  01  fe  96  00  08  01  00  cb  00  00  00  40  00
-EC 0x10:  00  00  ff  ff  f4  3c  87  09  01  ff  42  01  ff  ff  0d  00
-EC 0x20:  00  00  00  00  00  00  00  00  00  00  00  03  43  00  00  80
-EC 0x30:  01  07  1a  00  30  04  00  00  85  00  00  10  00  50  00  00
-EC 0x40:  00  00  00  00  00  00  14  01  00  04  00  00  00  00  00  00
-EC 0x50:  00  c0  02  0d  00  01  01  02  02  03  03  03  03  bc  02  bc
-EC 0x60:  02  bc  02  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0x70:  00  00  00  00  00  12  30  40  24  27  2c  27  21  80  1f  80
-EC 0x80:  00  00  00  06 *be  0d  03  00  00  00  0e  07  00  00  00  00
-EC 0x90:  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xa0:  ff  09  ff  09  ff  ff  64  00  00  00  a2  41  ff  ff  e0  00
-EC 0xb0:  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xc0:  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xd0:  03  00  00  00  00  00  00  00  00  00  00  00  00  00  00  00
-EC 0xe0:  00  00  00  00  00  00  00  00  11  20  49  04  24  06  55  03
-EC 0xf0:  31  55  48  54  35  38  57  57  08  2f  45  73  07  65  6c  1a
-
-Another set of values that varies often is the temperature
+	- use above mentioned tool to read out the EC
+
+Often fan and temperature values vary between
 readings. Since temperatures don't change vary fast, you can take
 several quick dumps to eliminate them.
 
@@ -1037,6 +1024,10 @@ ThinkPad-specific interface.  The driver will disable its native
 backlight brightness control interface if it detects that the standard
 ACPI interface is available in the ThinkPad.
 
+If you want to use the thinkpad-acpi backlight brightness control
+instead of the generic ACPI video backlight brightness control for some
+reason, you should use the acpi_backlight=vendor kernel parameter.
+
 The brightness_enable module parameter can be used to control whether
 the LCD brightness control feature will be enabled when available.
 brightness_enable=0 forces it to be disabled.  brightness_enable=1