ACPI: thinkpad-acpi: add brightness_force parameter

Add a "brightness_enable" module parameter that allows the local admin to
force the backlight support to not be enabled.

It can also be used to force the backlight support to be enabled, but that
is currently a no-op as the backlight support is enabled by default when
available.  This will be changed by a different patch.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index a743bfa62b9569e5ef84af7d96d84eb808e02a4a..f877c13c5ef812ed99df1673450cf1fae029662f 100644 (file)
--- 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 322ba25b47989039cf846f0b76b7741ee589a00a..56a21e6b80a96ae8bc4a5064912c3157d0acd789 100644 (file)
--- 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 8ca19c333727d0b0f73453c3956a9ec025fcf21f..8fba2bbe345ee3ad46808d7e522058d2983e8a97 100644 (file)
--- 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);