Re: [PATCH 3/6] Input: elantech - packet checking for v2 hardware

For v2 hardware, there is no real parity check, but we can still check
some constant bits for data integrity.

Signed-off-by: JJ Ding <redacted>
---
 drivers/input/mouse/elantech.c |   26 +++++++++++++++++++++++---
 1 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index cf41f23..032181c 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c

@@ -376,6 +376,25 @@ static int elantech_check_parity_v1(struct psmouse *psmouse)
 	       etd->parity[packet[3]] == p3;
 }
 
+static int packet_simple_check_v2(struct psmouse *psmouse)
+{
+	struct elantech_data *etd = psmouse->private;
+	unsigned char *packet = psmouse->packet;
+
+	if (etd->reports_pressure)
+		return (packet[0] & 0x0c) == 0x04 &&
+		       (packet[3] & 0x0f) == 0x02;
+
+	if ((packet[0] & 0xc0) == 0x80)
+		return (packet[0] & 0x0c) == 0x0c &&
+		       (packet[3] & 0x0e) == 0x08;
+
+	return (packet[0] & 0x3c) == 0x3c &&
+	       (packet[1] & 0xf0) == 0x00 &&
+	       (packet[3] & 0x3e) == 0x38 &&
+	       (packet[4] & 0xf0) == 0x00;