Commit 187ccd6c authored by Benjamin Tissoires's avatar Benjamin Tissoires Committed by Jiri Kosina
Browse files

HID: input: move up out-of-range processing of input values 



It actually makes sense to clamp the value to its boundaries before
doing further processing.

Signed-off-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: default avatarPing Cheng <ping.cheng@wacom.com>
Acked-by: default avatarPeter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent f2d4ddfa

drivers/hid/hid-input.c

+24 −24
Original line number Diff line number Diff line
@@ -1364,6 +1364,30 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct 
		return;

	}



	/*

	 * Ignore out-of-range values as per HID specification,

	 * section 5.10 and 6.2.25, when NULL state bit is present.

	 * When it's not, clamp the value to match Microsoft's input

	 * driver as mentioned in "Required HID usages for digitizers":

	 * https://msdn.microsoft.com/en-us/library/windows/hardware/dn672278(v=vs.85).asp

	 *

	 * The logical_minimum < logical_maximum check is done so that we

	 * don't unintentionally discard values sent by devices which

	 * don't specify logical min and max.

	 */

	if ((field->flags & HID_MAIN_ITEM_VARIABLE) &&

	    field->logical_minimum < field->logical_maximum) {

		if (field->flags & HID_MAIN_ITEM_NULL_STATE &&

		    (value < field->logical_minimum ||

		     value > field->logical_maximum)) {

			dbg_hid("Ignoring out-of-range value %x\n", value);

			return;

		}

		value = clamp(value,

			      field->logical_minimum,

			      field->logical_maximum);

	}



	switch (usage->hid) {

	case HID_DG_INVERT:

		*quirks = value ? (*quirks | HID_QUIRK_INVERT) : (*quirks & ~HID_QUIRK_INVERT);
@@ -1431,30 +1455,6 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct 
		break;

	}



	/*

	 * Ignore out-of-range values as per HID specification,

	 * section 5.10 and 6.2.25, when NULL state bit is present.

	 * When it's not, clamp the value to match Microsoft's input

	 * driver as mentioned in "Required HID usages for digitizers":

	 * https://msdn.microsoft.com/en-us/library/windows/hardware/dn672278(v=vs.85).asp

	 *

	 * The logical_minimum < logical_maximum check is done so that we

	 * don't unintentionally discard values sent by devices which

	 * don't specify logical min and max.

	 */

	if ((field->flags & HID_MAIN_ITEM_VARIABLE) &&

	    (field->logical_minimum < field->logical_maximum)) {

		if (field->flags & HID_MAIN_ITEM_NULL_STATE &&

		    (value < field->logical_minimum ||

		     value > field->logical_maximum)) {

			dbg_hid("Ignoring out-of-range value %x\n", value);

			return;

		}

		value = clamp(value,

			      field->logical_minimum,

			      field->logical_maximum);

	}



	/*

	 * Ignore reports for absolute data if the data didn't change. This is

	 * not only an optimization but also fixes 'dead' key reports. Some