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 <alex14...@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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/