acer-wmi: Blacklist backlight on Acer Aspire 1520 & 1360 series

A newer BIOS for these laptops adds ACPI-WMI support to them. However, it does
not add support for the backlight via the EC, and we have no way to detect
this on older machines, so blacklist it from them.

Signed-off-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
diff --git a/drivers/misc/acer-wmi.c b/drivers/misc/acer-wmi.c
index dd13a37..b82ff25 100644
--- a/drivers/misc/acer-wmi.c
+++ b/drivers/misc/acer-wmi.c
@@ -174,7 +174,7 @@
 struct quirk_entry {
 	u8 wireless;
 	u8 mailled;
-	u8 brightness;
+	s8 brightness;
 	u8 bluetooth;
 };
 
@@ -198,6 +198,10 @@
 static struct quirk_entry quirk_unknown = {
 };
 
+static struct quirk_entry quirk_acer_aspire_1520 = {
+	.brightness = -1,
+};
+
 static struct quirk_entry quirk_acer_travelmate_2490 = {
 	.mailled = 1,
 };
@@ -210,6 +214,24 @@
 static struct dmi_system_id acer_quirks[] = {
 	{
 		.callback = dmi_matched,
+		.ident = "Acer Aspire 1360",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 1360"),
+		},
+		.driver_data = &quirk_acer_aspire_1520,
+	},
+	{
+		.callback = dmi_matched,
+		.ident = "Acer Aspire 1520",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 1520"),
+		},
+		.driver_data = &quirk_acer_aspire_1520,
+	},
+	{
+		.callback = dmi_matched,
 		.ident = "Acer Aspire 3100",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
@@ -552,7 +574,8 @@
 	 * appear to use the same EC register for brightness, even if they
 	 * differ for wireless, etc
 	 */
-	interface->capability |= ACER_CAP_BRIGHTNESS;
+	if (quirks->brightness >= 0)
+		interface->capability |= ACER_CAP_BRIGHTNESS;
 
 	return AE_OK;
 }
@@ -1059,6 +1082,8 @@
 	printk(ACER_INFO "Acer Laptop ACPI-WMI Extras version %s\n",
 			ACER_WMI_VERSION);
 
+	find_quirks();
+
 	/*
 	 * Detect which ACPI-WMI interface we're using.
 	 */
@@ -1092,8 +1117,6 @@
 	if (wmi_has_guid(AMW0_GUID1))
 		AMW0_find_mailled();
 
-	find_quirks();
-
 	if (!interface) {
 		printk(ACER_ERR "No or unsupported WMI interface, unable to "
 				"load\n");