ACPI / video: ignore BIOS initial backlight value for HP Pavilion g6

commit 780a6ec6 upstream.

This patch addresses kernel bug 56661. BIOS reports an incorrect
backlight value, causing the driver to switch off the backlight
completely during startup. This patch ignores the incorrect value from
BIOS.

References: https://bugzilla.kernel.org/show_bug.cgi?id=56661Signed-off-by: Ash Willis <ashwillis@programmer.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/acpi/video.c

@@ -455,6 +455,14 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
 		DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion dm4 Notebook PC"),
 		},
 	},
+	{
+	 .callback = video_ignore_initial_backlight,
+	 .ident = "HP Pavilion g6 Notebook PC",
+	 .matches = {
+		 DMI_MATCH(DMI_BOARD_VENDOR, "Hewlett-Packard"),
+		 DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion g6 Notebook PC"),
+		},
+	},
 	{
 	 .callback = video_ignore_initial_backlight,
 	 .ident = "HP 1000 Notebook PC",