[PATCH 1/1] dell_laptop: add disable_backlight module parameter

[PATCH 1/1] dell_laptop: add disable_backlight module parameter

[Alex Davis]

I have a Dell Inspiron N7010 Laptop with Intel graphics. When the dell-laptop module is loaded,
two backlight device devices are created; dell_backlight, and intel_backlight from the Intel
graphics driver. The dell_backlight device is non-functional, but the graphics subsystem uses
it instead of the functioning intel_backlight device. The result is that, when running KDE,
screen dimming does not work. I've added a module parameter, disable_backlight, which when 
true will disable the dell_backlight device, and leave only the intel_backlight: with this,
screen dimming works.

Signed-off-by: Alex Davis <alex14641@yahoo.com>
--- dell-laptop.c.orig    2013-12-01 19:05:39.693149050 -0500
+++ dell-laptop.c    2013-12-01 17:29:27.613372482 -0500
@@ -35,6 +35,9 @@
 /* This structure will be modified by the firmware when we enter
  * system management mode, hence the volatiles */
 
+static bool disable_backlight;
+module_param(disable_backlight, bool, 0644);
+
 struct calling_interface_buffer {
     u16 class;
     u16 select;
@@ -561,6 +564,9 @@ static int __init dell_init(void)
 
     dell_laptop_dir = debugfs_create_dir("dell_laptop", NULL);
 
+    if (disable_backlight)
+        return 0;
+
 #ifdef CONFIG_ACPI
     /* In the event of an ACPI backlight being available, don't
      * register the platform controller.




I code, therefore I am 

Re: [PATCH 1/1] dell_laptop: add disable_backlight module parameter

[Alex Davis]

>On Sunday, December 1, 2013 8:43 PM, Alex Davis <alex14641@yahoo.com> wrote:
>I have a Dell Inspiron N7010 Laptop with Intel graphics. When the dell-laptop module is >loaded,
>two backlight device devices are created; dell_backlight, and intel_backlight from the >Intel
>graphics driver. The dell_backlight device is non-functional, but the graphics subsystem >uses
>it instead of the functioning intel_backlight device. The result is that, when running >KDE,
>screen dimming does not work. I've added a module parameter, disable_backlight, which when 
>true will disable the dell_backlight device, and leave only the intel_backlight: with >this,
>screen dimming works.
>
>Signed-off-by: Alex Davis <alex14641@yahoo.com>

This patch is against 3.10.