3 files changed, 14 insertions, 0 deletions

diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index a743bfa62b95..f877c13c5ef8 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -944,6 +944,10 @@ When display backlight brightness controls are available through the
 standard ACPI interface, it is best to use it instead of this direct
 ThinkPad-specific interface.
 
+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.
+
 Procfs notes:
 
         The available commands are:
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 322ba25b4798..56a21e6b80a9 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -3182,6 +3182,12 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 
         mutex_init(&brightness_mutex);
 
+        if (!brightness_enable) {
+                dbg_printk(TPACPI_DBG_INIT,
+                           "brightness support disabled by module parameter\n");
+                return 1;
+        }
+
         if (!brightness_mode) {
                 if (thinkpad_id.vendor == PCI_VENDOR_ID_LENOVO)
                         brightness_mode = 2;
@@ -4803,6 +4809,9 @@ module_param_named(fan_control, fan_control_allowed, bool, 0);
 static int brightness_mode;
 module_param_named(brightness_mode, brightness_mode, int, 0);
 
+static unsigned int brightness_enable = 2; /* 2 = auto, 0 = no, 1 = yes */
+module_param(brightness_enable, uint, 0);
+
 static unsigned int hotkey_report_mode;
 module_param(hotkey_report_mode, uint, 0);
 
diff --git a/drivers/misc/thinkpad_acpi.h b/drivers/misc/thinkpad_acpi.h
index 8ca19c333727..8fba2bbe345e 100644
--- a/drivers/misc/thinkpad_acpi.h
+++ b/drivers/misc/thinkpad_acpi.h
@@ -339,6 +339,7 @@ static int bluetooth_write(char *buf);
 static struct backlight_device *ibm_backlight_device;
 static int brightness_offset = 0x31;
 static int brightness_mode;
+static unsigned int brightness_enable;  /* 0 = no, 1 = yes, 2 = auto */
 
 static int brightness_init(struct ibm_init_struct *iibm);
 static void brightness_exit(void);