From: Jeff Mahoney Subject: [PATCH] thinkpad_acpi: Fix oops with incompatible backlight interface Mainline commit 2dba1b5d87e08a294da5cdfa4d32908000e9b085 (trenn's patch thinkpad_fingers_off_backlight_igd.patch added new users of ibm_backlight_device. brightness_init() returns -errno on fatal errors and 1 if the interface is incompatible. This leaves ibm_backlight_device == NULL, which causes an oops in hotkey_notify(). This patch adds a check for ibm_backlight_device. Signed-off-by: Jeff Mahoney --- drivers/misc/thinkpad_acpi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/misc/thinkpad_acpi.c +++ b/drivers/misc/thinkpad_acpi.c @@ -2401,7 +2401,7 @@ static void hotkey_notify(struct ibm_str case 1: /* 0x1000-0x1FFF: key presses */ scancode = hkey & 0xfff; - if (tp_features.bright_igdmode) { + if (tp_features.bright_igdmode && ibm_backlight_device) { /* ToDo: * Is there an already defined key? */