USB HID: numlock quirk for dell W7658 keyboard

On Dell W7658 keyboard, when BIOS sets NumLock LED on, it survives the
takeover by kernel and thus confuses users.

Eating of an increasibly scarce quirk bit is unfortunate. We do it for safety,
given the history of nervous input devices which crash if anything unusual
happens.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/usbhid/hid-core.c

@@ -129,6 +129,9 @@ MODULE_PARM_DESC(mousepoll, "Polling interval of mice");
 #define USB_DEVICE_ID_CYPRESS_HIDCOM	0x5500
 #define USB_DEVICE_ID_CYPRESS_ULTRAMOUSE	0x7417
 
+#define USB_VENDOR_ID_DELL		0x413c
+#define USB_DEVICE_ID_DELL_W7658	0x2005
+
 #define USB_VENDOR_ID_DELORME		0x1163
 #define USB_DEVICE_ID_DELORME_EARTHMATE 0x0100
 #define USB_DEVICE_ID_DELORME_EM_LT20	0x0200
@@ -469,6 +472,8 @@ static const struct hid_blacklist {
 	{ USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_FOUNTAIN_TP_ONLY, HID_QUIRK_POWERBOOK_HAS_FN | HID_QUIRK_IGNORE_MOUSE },
 	{ USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_GEYSER1_TP_ONLY, HID_QUIRK_POWERBOOK_HAS_FN | HID_QUIRK_IGNORE_MOUSE },
 
+	{ USB_VENDOR_ID_DELL, USB_DEVICE_ID_DELL_W7658, HID_QUIRK_RESET_LEDS },
+
 	{ 0, 0 }
 };
 
@@ -963,6 +968,44 @@ void usbhid_init_reports(struct hid_device *hid)
 		warn("timeout initializing reports");
 }
 
+/*
+ * Reset LEDs which BIOS might have left on. For now, just NumLock (0x01).
+ */
+static int hid_find_field_early(struct hid_device *hid, unsigned int page,
+    unsigned int hid_code, struct hid_field **pfield)
+{
+	struct hid_report *report;
+	struct hid_field *field;
+	struct hid_usage *usage;
+	int i, j;
+
+	list_for_each_entry(report, &hid->report_enum[HID_OUTPUT_REPORT].report_list, list) {
+		for (i = 0; i < report->maxfield; i++) {
+			field = report->field[i];
+			for (j = 0; j < field->maxusage; j++) {
+				usage = &field->usage[j];
+				if ((usage->hid & HID_USAGE_PAGE) == page &&
+				    (usage->hid & 0xFFFF) == hid_code) {
+					*pfield = field;
+					return j;
+				}
+			}
+		}
+	}
+	return -1;
+}
+
+static void usbhid_set_leds(struct hid_device *hid)
+{
+	struct hid_field *field;
+	int offset;
+
+	if ((offset = hid_find_field_early(hid, HID_UP_LED, 0x01, &field)) != -1) {
+		hid_set_field(field, offset, 0);
+		usbhid_submit_report(hid, field->report, USB_DIR_OUT);
+	}
+}
+
 /*
  * Traverse the supplied list of reports and find the longest
  */
@@ -1348,6 +1391,8 @@ static int hid_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
 	usbhid_init_reports(hid);
 	hid_dump_device(hid);
+	if (hid->quirks & HID_QUIRK_RESET_LEDS)
+		usbhid_set_leds(hid);
 
 	if (!hidinput_connect(hid))
 		hid->claimed |= HID_CLAIMED_INPUT;

include/linux/hid.h

@@ -269,6 +269,7 @@ struct hid_item {
 #define HID_QUIRK_SONY_PS3_CONTROLLER		0x00080000
 #define HID_QUIRK_LOGITECH_DESCRIPTOR		0x00100000
 #define HID_QUIRK_DUPLICATE_USAGES		0x00200000
+#define HID_QUIRK_RESET_LEDS			0x00400000
 
 /*
  * This is the global environment of the parser. This information is